I'll join if you'll have me.

1.) Imperial Fists (because the ability to craft fortifications is a good plot device)
2.) Dark Angels (because hunting the fallen is a fun plot device)
3.) New Chapter (because this gives the ability for the GM to be flexible with all your characters and simply say "well thats just how this chapter is", and it gives the possibility to include flavors from many chapters all under one roof.) I'd keep the progenitor a secret to keep the flexibility.

Remember there's nothing to say you can't play a particularly stealthy Imperial Fist or a scout with a penchant for bionics from any other chapter. You dont have to be "type-cast".

Right now I'm thinking of going a boltgun scout, but i need to brainstorm an appropriate skill set for him. I prefer to keep the equipment simple but go wild with the skills.