There have been some truly magnificent talents pass through the TUF household over the years but who's gone on to become the best? My list goes as:
1. Rashad Evans
2. Matt Brown
3. Nate Diaz
4. Forrest Griffin
5. Michael Bisping
6. Kelvin Gastelum
7. Big Country
8. Matt Serra
9. Kenny Florian
10. Diego Sanchez
Rashad is the easy number 1. Having Diaz and Brown over Griffin is a travesty. Serra is also a high mention, but giving the unusual nature of Season 4, it's hard to say where he should end up.
If we look at it from a numbers game, Rashad, Forrest, and Serra became champs. Diaz, Florian, Dodson, Koscheck, Cote and Sanchez all fought for the belt, and Dillashaw is on his way. Gastelum shows a lot of promise, but I won't bite until he beats a guy in the top 10. Bisping, Big Country, and Brown have done well for themselves, but have yet to win against a top 10 fighter either. Bonnar gets a slight reference as honorable mention.
So if I had to make a list, it would be 1. Rashad, 2. Forrest, 3. Serra, with 4-10 some mix of the other mentioned fighters outside of Bonnar/Cote/Gastelum/Brown. Bisping gets the nod over Brown in my book based solely on strength of schedule, even though he lost all of his bigger fights. Also, Serra could drop to 4 and switch with maybe Florian, Koscheck, or Sanchez.
If I missed a TUF fighter/winner who fits into the above categories, I apologize.
EDIT: Nelson has a top 10 win I'm pretty sure, and I forgot Joe Lauzon as well.