A key consideration to making decisions like these is the purpose of doing so, which is not clear to me. How I'd do it for a game is different from how I'd do it for a story, and likely both are different for how I'd choose a batch of mechs to give similar paint jobs for display purposes.
I'd likely choose a Marauder or Archer over an Awesome. Keeps to canon flavor better, and I just don't like slow assaults. I'd likely keep the Jagermech, but if I did switch it out, it would be to a Rifleman, which I've always considered a standard Suns mech. It often doesn't get the same respect that it did back in the early days of the game, and its fluff purpose has changed, but it would still be a good fit.
I'd be happy leaving the fast Enforcer in the command lance. I don't see the movement wasted, I see it being the scout for the lance. Because this lance will be going against heavier opposition, it needs a heavier scout. But, in my experience, this works better in a story than in a game, so if the purpose is to create a game unit, I'd change it out with a slower unit.
I've read (somewhere, no idea where) that the Suns didn't worry about unit composition as much as other factions, and instead dropped whatever was available into an open slot. It was up to the unit to figure out how to work together. So, unlike other factions, I rarely try to optimize Suns units by speed or weight, and instead purposely mix them up. Other factions have scout, assault, fire, and strike lances, whereas the Suns often have one of each type in the same lance. My Suns lances are more general purpose, jack-of-all trades type affairs.
