Always a tough topic since there are so many fighters. These guys IMO are the divisional greats and a lock for top 7.
1.Jones
2.Anderson
3.GSP
4.Fedor
5.DJ
6.Aldo
7.Khabib
Then it gets tough cause there are so many fighters that have done great things and vary in the criteria. You got Volk, Usman, Izzy, Stipe, and Islam of recent years with the title defenses and great streaks. You got guys like Nogueira and Wanderlei who in his prime did incredible things in Pride in a long span of fights. You got guys like DC who have shorter careers but have accomplished a lot in a short time. I think the above are a lock, but the next 3 need some explanation.
8. Daniel Cormier - 2 division UFC champ defending both belts, Strikeforce HW GP champ with a great HW roster, 22-3 record with 2 losses coming at the end of his career and a great resume of top fighters.
9. Big Noguiera - Pride and UFC HW champ, great record, and the highest number of top 10 wins of any fighter and a great resume of top fighters beaten.
10. Volk - great champion with 5 defenses, great record and only lost to one guy in his division, great resume. I think the best of the recent great champions. And I am putting Volk in here under the assumption he beats Lopes.