Those are 2 separate arguments you have. One of your opinions is "UFC has the best champs", while your other opinion is "UFC has the best fighters".
UFC currently has good champs. That doesn't mean UFC has concrete top 10's. Bellators Will Brooks can beat majority of UFC's very strong top 10 LW. Bellators Liam McGeary can beat the majority of UFC LHW. I also think Bellators Strauss can beat majority of UFC's Featherweights. Can they beat UFC's current champs in those relative divisions? Maybe not... but 80-90% of UFC top 10's can't beat the current champ in those relative divisions. So UFC doesn't have the "best fighters". They do have the best "champs", but their champs also beat the shit out of all their top 10's, so there is an obvious competitive gap between UFC's champs and top 10's, ala Barao, Aldo, Ben Henderson, RDA, DC, Bones Jones, Spider and Cain.