Best tank combo would be tanks that have skill, regardless of what class they play. I have seen exceptionally well tankadins and druids. The debate over which class is the best at tanking or holding aggro isn't really class specific imo, BUT, I do hate running heroics with 4/5 t4::1/5 T5 tanks that open up every fight with TAUNT! I just laugh at them, after I ask them why they do it.
I had one tank tell me that he doesn't use Shield Slam because its a waste of rage or it takes too much rage for it. Then he told me that he thinks revenge is overrated and won't do that either. So, I watch his threat slowly build, then I DPS. Needless to say he just did the sunder thing and let the healer and CC die because I couldn't hold aggro on the other mobs. Oh, this is in Heroic SV btw. On the other hand, I have seen warriors with the same gear just rape heroics!! I had a guy go through Heroic UB and he pulled so much aggro on all the multiple mob pulls that I could SS and WW and still not pull (most of the time) and when I did, our healer was leet enough to toss me heals. Smooth as butter.
I've seen druids and paladins do the same thing. So...it really depends on who is doing the tanking, albeit, I think pali's hold the standard for multi mob tanking though!