Fedor, Silva, GSP, Aldo, Jones
Fedor was a LHW who fought HW when it was at its best(by far).
Silva had 10 title defenses but its how easy he made them look. The one title fight that was actually difficult(Sonnen 1) he pulled of a triangle in the last 5-10 seconds of the fight. It was like MJ at the buzzer.
GSP is probably the most complete MMA fighter of the list. Sure some people considered him boring but the fact is he was striker who became the best MMA wrestler and used that to completely nullify most of his opponents. GSP was a professional champion. You just can't imagine GSP not having the belt.
Aldo is ahead of Jones in my opinion because 1)he deserves it and 2)Jones deserves to be put behind Aldo. Aldo was a very dominant champion and extremely well rounded. Probably the best TDD ever and a great fundamental striker that could be explosive at times. His TDD and striking was so great that to this day we have never seen his BJJ, which is supposed to be on par with the rest of his skill set. Aldo also fought his title fights(UFC/WEC) against contenders that were in their prime or at least young. Unlike Jones who fought guys like Shogun, Rampage, Rashad, Chael, and Vitor when they were beyond their prime.