This question is spurred on following UFC 145's main event. The heavyweight bout is a useful example of the topic I'm discussing. Both JDS and Cain have been absolutely dominant to the rest of the fighters in the division. In the case of JDS, for example, when he fought the then No #1 contender in Frank Mir, he lit him up like a Christmas tree and the skill gap was... well let's just say that it was more than obvious. The same could also be said for Cain and his brutal exercise over Big Foot.
So my question would be: do you agree that there is a massive skill differential that separates the top 2 or 3 in the HW division with the rest? What other divisions do you guys think this applies to? MW would be a prime example of what I'm talking about.
Discuss.
I don't think this is quite true with heavyweight.
IMO: Cain, Junior, Cormier, Overeem and Werdum are a clear top 5 that could probably all beat each other on a given day. If they all fought in a roundrobin right now, no fighter would go 5-0.
Jon Jones looks light years ahead of everyone else at 205, though I'm optimistic that Machida can give him an even better fight next time, but you'd have to say lhw has a very clear and undisputed top 1.
185 looks the same with Anderson, though most people seem to think that Chris Weidman is a very legit and dangerous challenger because of his particular attributes - the problem there is that Weidman hasn't beaten any top 5 guys yet; for all we know he could become unstuck against a genuine top contender like Vitor Belfort. I'd like to see Weidman fight Belfort or Okami before saying 185 has a clear top 2, for now Silva is head and shoulders above the rest.
Although GSP is the bona fide number 1, I think welterweight is one of the only divisions where there is no 2-3 fighter elite at the top, the division is just too deep and GSP has shown in recent fights with Shields and more especially Condit that he can't just blow guys out of the water anymore. Right underneath GSP you have a lot of excellent guys who could all beat each other IMO: Hendricks, Condit, Rory MacDonald, Nate Marquardt, Maia, Kim, Koscheck, Fitch, Erick Silva, Nick Diaz, Ellenberger, Story, Kampmann, Alves.
Lightweight is more problematic. I personally view Benson Henderson as an unassailable number 1 like Jones or Anderson or GSP, but I know most people don't yet. Realistically, I think the only legit challenge for Benson is Anthony Pettis, but even then I'd strongly favour Ben. Although lightweight is also a deep division, I don't believe any of the top guys stand much of a chance against a guy who is going to become a very long-reigning and dominant champion.
Featherweight now does fit your description very well. I believe Aldo and Edgar are light years ahead of the chasing pack. The next best guys in that division (Korean Zombie, Siver, Guida, Mendes, Koch) are quite a way behind them. Those two will fight more than once IMO.
Bantamweight: Yes as well. Barao and Cruz way out in front. The best of the rest (Faber, Wineland, McDonald) aren't quite on the same level.
Flyweight: No. Demetrious Johnson could be beaten on a given day by McCall, Dodson, Benavidez. All those guys are closely matched.
So in my opinion,
Heavyweight: elite group
LHW: elite 1
MW: elite 1
WW: elite 1 with very good group immediately below
LW: elite 1
FW: elite 2
BW: elite 2
FW: elite group
So for me, only featherweight and bantamweight fall into your category of having two fighters significantly better than everyone else - which is better than lhw, mw and lw which have one outstanding fighter and not much challenges for them. WW has an elite fighter but many dangerous challenges ahead.