I was going to say Zombie, too.
Fan favorite who was really good (both fought for a title), but was a win some, lose some kind of guy.
The real answer of course is there isn't one.
I don't think Chito was ranked, actually, but yeah, Conor had lost prior to coming to the UFC and although I think Chito was winning that fight, it was still a fluke injury that ended it.
Poirier was ranked #5 if memory serves, so yeah, not the #1 contender, but it was still a "if you beat a top 5 guy, we'll give you a title shot".
Side note, is there not a website that tracks what guys were ranked at the time?