Of course the Original is the best.
Plus I always go to the Family Members first when we need a replacement.
Crystal, She Hulk, Luke Cage. Those kinda guys.
But if I were to make up a new one without any ties to the old, I'd choose according to powers that compliment the old FF.
So here's a new lineup.
Hank Pym - Ant Man - Giant Man - Goliath - Yellowjacket
Brilliant. When replacing Reed you have to remember that it's not just the size alteration, it's his mind that's the real super power. Hank is no slouch in this department and is easily one of the most adaptable heroes in the 616. Plus he can grow or shrink to help in the way that Reed always did with his elongation.
Rachael Summers - Marvel Girl - Phoenix
Telekinesis that can match up to Sue's forcefields. Plus with her telepathy she can become "invisible" as well. Plus the woman of the group must have a relationship with Franklin. Heh.
Sunfire
Gotta replace a hothead with a hothead. Sunfire fits the bill perfectly. And if you ask me he's the second most powerful flame wielder in the 616. Screw Pyro! Sunfire rocks!
Collossus
If you are gonna replace the Thing, you better find a scrapper with a heart of gold. Nobody fits the bill in my mind better than Piotr Rasputin.
So there you have it. The Worlds Greatest Team Reborn.