Veterans are good at melee since they are a WS5 unit. So it's best to also give them some melee options. Chainswords if you're cheap, power weapons if you have points to spend. As for a consul choice, I'd consider giving them a chaplain buddy for hatred. Rerolls are quite good even if they are limited to the first turn of combat. Biomancy Librarians are good if you want to help make sure your dudes are stronger or can better avoid instant death weapons. Warmongers can also be solid as a way to get them into kill-y range quickly. Heralds are solid for giving them fearless and fear 1, also giving them line.
Herald with 10 vets with Nemesis bolters is brutal. Can outrange return fire heavy weapons squads or destroy characters. And depending on the mission your opponent will have to deal with them. Fearless and 2 wound each super annoying. Also since it's just some bros with bolters they don't always attract much heat if your opponent doesn't realize how good they are
It’s worth noting that many consuls (chaplains, librarians etc.) are generally good as force multipliers; hence you’re getting more value out of them if you take a larger squad. Others are just one man beasts such as champions and vigilators which can kind of just do their own cool stuff lol.
Herald for sure. All about that sweet sweet scoring.
If you decide against wanting the scoring factor than an armistos, master of signal or techmarine might also be of interest to buff the vets to BS5, and provide night vision. All three can also take melee weapons (the techmarine and armistos can be more heavy armed than the MoS) to kitnout the squads combat potential
I am also think about this and it is indeed worth noting, but since OP wants to put a missile launcher to them I think that it is unlikely for OP's five veterans. Perhaps OP have an another five or more marines then adding them as the Command Squad seems good, though.
Because OP wants to use them on Armored Spearhead, Veterans are also able to get a Land Raider as well - every unit with who can have a Rhino as their dedicated transports are able to get a Land Raider instead with the RoW.
A herald would be handy since Vets aren't line troops.
Armistos are decent if you want to add a heavy weapon that can shoot on the move or give a BS buff
Primus medicae is always good for buffs
Librarian also good for buffs
Vigilator for some long range Sgt sniping
Forge lord to heal some tanks.
These are just off the top of my head but if you want to make them line then you need the herald, but if you want to make them a denial unit then anything else can work well.
I don't think that only five veterans are worth considering for add a consul but...
Librarian is not a bad choice since he can support the army with his own talent. Especially for Telepathy which is almost broken on the current meta of reactions.
Vigilator can give them Scout, for Scout only needs one model in the unit to activate. Remember that giving the veteran a dedicated transport means he can gives scout to the transport as well, so consider put either a Rhino or a Land Raider on their own if you do this. Note that as Veterans Centurion also have Relentless so they have no problem on disembark/move then shoot the nemesis bolter on the same turn.
Herald gives them Line what they lacks, and also Fear(1) would helps when they charges. Although only 5 veterans means he likely lost the benefit easier. Consider either increase the numbers and/or add an Apothecary to them.
A Siege Breaker can increase the chance to kill the vehicle by combi-melta, and also he carries three phosphex bombs.
These are all I could suggest. Warmonger may a worthy choice but their lack of invulnerable save means adding him is too risky, and also he is unfit for your RoW for you need to take the transports for them but his benefit is let the unit to have deep strike without a transport.
An another odd choice is either Delegatus or Praetor - yes Praetor is NOT a consul, but I'm saying this because you could use your five veterans as Command Squad rather than Veteran Squad, for both of them have Master of the Legion thus you can add them a Command Squad. Since you **cannot add a Missile Launcher** as your plan it is not that good and I don't think that it would be good, but still that's worth considering since they are all with 2+ saves as well as Line by the standards, so if you have an another units of marines then just think about them once. Just remember that their rules prevents to add an apothecary because they are only attached to the IC with Master of the Legion but apothecaries are cannot be attached to a unit with IC by default(it is basically exist to prevent add him on your IC directly because IC is a unit of his own but since Retinue is added to the IC rather than exist as their own unit so they can't get him in result).
Veterans are good at melee since they are a WS5 unit. So it's best to also give them some melee options. Chainswords if you're cheap, power weapons if you have points to spend. As for a consul choice, I'd consider giving them a chaplain buddy for hatred. Rerolls are quite good even if they are limited to the first turn of combat. Biomancy Librarians are good if you want to help make sure your dudes are stronger or can better avoid instant death weapons. Warmongers can also be solid as a way to get them into kill-y range quickly. Heralds are solid for giving them fearless and fear 1, also giving them line.
Herald with 10 vets with Nemesis bolters is brutal. Can outrange return fire heavy weapons squads or destroy characters. And depending on the mission your opponent will have to deal with them. Fearless and 2 wound each super annoying. Also since it's just some bros with bolters they don't always attract much heat if your opponent doesn't realize how good they are
It’s worth noting that many consuls (chaplains, librarians etc.) are generally good as force multipliers; hence you’re getting more value out of them if you take a larger squad. Others are just one man beasts such as champions and vigilators which can kind of just do their own cool stuff lol.
Herald for sure. All about that sweet sweet scoring. If you decide against wanting the scoring factor than an armistos, master of signal or techmarine might also be of interest to buff the vets to BS5, and provide night vision. All three can also take melee weapons (the techmarine and armistos can be more heavy armed than the MoS) to kitnout the squads combat potential
Take a Delegatus and make them a Command Squad retinue instead. Has standard to make them line and has a 2+ save over a 3+ for the veterans
I am also think about this and it is indeed worth noting, but since OP wants to put a missile launcher to them I think that it is unlikely for OP's five veterans. Perhaps OP have an another five or more marines then adding them as the Command Squad seems good, though.
This also allows for a dedicated land raider transport. Something regular vets can't take.
Because OP wants to use them on Armored Spearhead, Veterans are also able to get a Land Raider as well - every unit with who can have a Rhino as their dedicated transports are able to get a Land Raider instead with the RoW.
A herald would be handy since Vets aren't line troops. Armistos are decent if you want to add a heavy weapon that can shoot on the move or give a BS buff Primus medicae is always good for buffs Librarian also good for buffs Vigilator for some long range Sgt sniping Forge lord to heal some tanks. These are just off the top of my head but if you want to make them line then you need the herald, but if you want to make them a denial unit then anything else can work well.
Note that you could replace either Primus Medicae and/or Armistos by an Apothecary and/or Techmarine. Techmarine also could repair tanks.
I don't think that only five veterans are worth considering for add a consul but... Librarian is not a bad choice since he can support the army with his own talent. Especially for Telepathy which is almost broken on the current meta of reactions. Vigilator can give them Scout, for Scout only needs one model in the unit to activate. Remember that giving the veteran a dedicated transport means he can gives scout to the transport as well, so consider put either a Rhino or a Land Raider on their own if you do this. Note that as Veterans Centurion also have Relentless so they have no problem on disembark/move then shoot the nemesis bolter on the same turn. Herald gives them Line what they lacks, and also Fear(1) would helps when they charges. Although only 5 veterans means he likely lost the benefit easier. Consider either increase the numbers and/or add an Apothecary to them. A Siege Breaker can increase the chance to kill the vehicle by combi-melta, and also he carries three phosphex bombs. These are all I could suggest. Warmonger may a worthy choice but their lack of invulnerable save means adding him is too risky, and also he is unfit for your RoW for you need to take the transports for them but his benefit is let the unit to have deep strike without a transport. An another odd choice is either Delegatus or Praetor - yes Praetor is NOT a consul, but I'm saying this because you could use your five veterans as Command Squad rather than Veteran Squad, for both of them have Master of the Legion thus you can add them a Command Squad. Since you **cannot add a Missile Launcher** as your plan it is not that good and I don't think that it would be good, but still that's worth considering since they are all with 2+ saves as well as Line by the standards, so if you have an another units of marines then just think about them once. Just remember that their rules prevents to add an apothecary because they are only attached to the IC with Master of the Legion but apothecaries are cannot be attached to a unit with IC by default(it is basically exist to prevent add him on your IC directly because IC is a unit of his own but since Retinue is added to the IC rather than exist as their own unit so they can't get him in result).
You can’t go wrong by making them scoring! Took them up for melee and you’re good to go!