Exactly Cro Cop make Coleman look almost retarted in that fight. Coleman was past his prime but he would have used the same strategy had it been 1997 and still got KTFO early.
While Coleman may not be worthy of top 3, I wouldn't go as far as to drop him below Sylvia and Arlovski. OK he didn't adapt and has some pretty bad losses on his record but he won two(?) UFC tournaments, was the first UFC HW champ and won the 2000 Pride GP. Those achievements alone eclipse anthing either Sylvia and Arlovski have done imo, although I'll admit Coleman's record does fall short in terms of names. Apart from that your list isn't bad either. TBH, once you get past the top 5 or so, the list gets a bit iffy and there could be a few names you could throw in. Not surprising really considering that MMA is a relatively young sport.
Coleman though has a UFC HW title and a Pride GP title. CroCop can never point to one point in time where he could say he was the best, Coleman can.