So from a almost pure pvper's perspective, Cata was the best WoW has ever offered. Don't believe me because you can't 1v1 every class in the game and the one time you tried to arena with hunter/hunter/hunter you didn't get past 1200?
I'm not saying Cata pvp is perfect. Far from it. Cata pvp had/has problems. But let's compare it to the other expaks:
Vanilla: hahaha, I'm not even going
BC: s1-2 had broken warlocks whose damage was unaffected by resilience as well as overpowered CC, Paladins, and a lot of other problems. Gear was obtainable without rating restriction. s3-4 were probably the second best WoW has ever offered as most of the initial problems were solved. Druids completely dominated the healing landscape with 40 yard range cyclones, infinite mana, lifebloom, etc. Gear was obtainable without rating restriction except for shoulders and weapon.
Wrath: s5 had the debut of incredibly overpowered DKs, incredibly overpowered Rethealers/Prothealers, and the even more mind boggling overpowered survival hunters. Gear was obtainable through a complicated rating system that applied to every single piece of gear. s5 was the worst season in arena history. Vanilla was arguably worse, but only arguably. s6 and on was just OH MY GOD BURST. Wrath's pvp sucked dick.
Cata: Initially ferals dominated with insane dot dps, insane uptime, no ability to be controlled (can't root, can't slow, can't fear, can't polymorph) but after some nerfs were brought under control. Warriors then became the problem with Swifty Macros that could one shot entire opposing BG teams. Shamans still had complete immunity to fear due to tremor totem and dominated the healing landscape. Gear is obtainable without restriction, except for weapons, which are both on a timer and have high rating t2 versions. (This is the best gear treadmill ever seen in pvp, and I hope they stick to this model.) The current state of the game has overpowered Warlock/Shaman synergy, and the most glaring problems of Shadow Priests with their burst trinket and Rogues with Vial. Resto druids are laughable and any team that uses a warrior could probably be improved by swapping in a rogue with vial. All in all, more team comps are viable then any other point in arena history, and rated bgs give an alternative way to gear up as well as allowing some less viable arena specs to shine (hunters, boomkins, ele shamans are all amazing in bgs. They can all be viable in arena as well, but you need a lot of skill in comparison to, say, anything that melees).
tl;dr: I'm currently farming for Vial so I too can be completely ridiculous