I don't think you quite understand the essence of this kind of Roleplay, not to sound rude, but it comes off as if you think there's a universal consensus over who's the best and worst.

Of all the Arena Roleplayers I can consistently write posts of any length and quality depending on who I'm roleplaying with. I like to match whoever I'm writing against, sometimes adding in an extra paragraph or two for good measure. 

Am I the best? No.

But I'm certainly not the worst. 

There is no 'best' in Arena Roleplay. Anyone who claims to be the best has this bad habit of godmodding when put on the spot. I like to think that there's five levels of Arena Roleplayers.

Newbies: People who have played for only a little while, or have played on and off but were never great.
Casuals: Your average Arena Roleplayer, they'll post now and then and can write respectable posts. Nothing that excels beyond the norm, but respectable.
Competitive: The usual sort that you'll attract with a large scale arena, they've been at this for a while and are good at it. Taking pride in their posts and putting feeling into them.
Advanced: Have been playing longer than most, can write astonishing ranges of posts detailing any number of action. Some of the best reside in this category.
Remarkable: And here's the best, alright, maybe not the best. But they can outwrite a good number of roleplayers and back all but the best into corners. They've put time, effort, and passion into their roleplaying. And it really shows.

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Now, if you'd like to step into the ring with a couple of our favorite characters I'd show you what I've got. Because I tend to enjoy peacocking how good I am when I'm really into a roleplay.