For PvP, I'll just give my like top whomever, since I actually have reasoning (not trying to argue, throwing in my opinion)
1. Optimism - Greatest pvper of all time no doubt. Adapts to any style, can use each and every skill without losing, and can adequately fight anything that's thrown against him.
2. Starscream55 - I've seen from experience star's much-better-than-average timing and reaction time, and with the correct techniques, star can pummel almost anyone, if he's focused.
3. ImaginationX - He didn't used to be that good, but determination has allowed him to severely improve his timing and reaction time, similar to star, except that Imag actually managed to create his OWN rush technique. Unless someone were to master how to tear down his rush technique, Imag definitely deserves top three.
4. Rossbach - Going for an incredible stretch here, but Ross's ability to get away from an opponent, and bring them within a pushable range definitely must count for something. A push is a kill, no matter how much the opponent rages about it.
5. Allie - I'm putting myself this high not for ego (else I'd rank myself higher), but because I fight solely without a skill. I am among the only pvpers who learned to fight with only the default style, and my ability to focus when necessary (in 1v1s, above all) is definitely something that any good pvper notices, allowing me to defeat nearly anyone who doesn't lag (though I blow against lag, incredibly).
6. Ninja - Putting him this low possibly because he's rusty, but from what I've seen, he makes mistakes consistently whilst using his rush techniques. However, he deserves a prominent place in the top 10 pvpers due to his ability to fight while NOT making mistakes. If you can trick Ninja, you'll have a chance, else you're a goner.
7. Corr - Corr certainly may believe he deserves much higher on this list, but I believe (as did most of the top pvpers) that he's mostly all talk (and horrid technique). Corr's main techniques include running and guarding on the fences of flop. It's just an advanced version of lyric, running the entire game - effective but hardly considered a professional method of PvP.
8. Yz - While able to efficiently use lag, the base skill that I'VE seen from Yz is mediocre at best. Due to being a complete lagfest, Yz learned how to abuse his lag to the furthest extent he can, instead of how to PvP most efficiently. This is only judged from the videos he's released of him PvPing, but I see consistent mistakes and horrible flow from almost all of them - no offense Yz.
That's all I can think of atm. These are strictly my opinions and from my experiences whilst PvPing (and watching them PvP), so anyone I do not (or did not) actively PvP are not included in this list.