Which champion is better and plays its role better? I play Rengar Jg and that is my main, but im looking for a really nice mid laner and when playing Azir mid I did great and loved his mechanics ( During free rotation) . But when I talk to other players about who to play jg they say Hecarim is the ultimate jungler and I feel that if imma main jungle I need him. So who is it? 
or 
plz leave a vote if your looking at this.
Hecarim is not a great jungler. I would say Rek'Sai and Sej are better. This is coming from a former Jungle Hec main. If you are going to go Jungle Hec, you should bring Smite/TP for global pressure, as Homeguard/TP is his best strategy.
This may sound weird, but are you planing to go mid lane at all?
If so, and you really like Azir, then go for him. Currently you have Rengar, as your jungler. If you really desperately need a mid laner then yeah, get Azir if you like his style.
Hecarim, in the jungle in my experience is fun. If you are total trash at the jungle, like I am, he can help you improve and learn on a champ that is a bit more forgiving when taking damage due in part to his W. His clear speed is pretty meh, especially if you are again trash like me. But overall he is pretty good and offers a bit more mobility or rather encourages it with his passive that makes it so that you can increase his AD with move speed. That is the main thing right there, MOVE SPEED.
If Hecarim isnt a good champ then who is? A champion with a diffrent feel to it that is also fun and viable.
