In truth... I've not too much experience in the zones... Nor Do I know or witness a lot of battles. But I'll give my list.
2.) Shigeo
3.) Court
4.) Makoto
5.) Raifudo
6.) Xiarawst
7.) Ranketsu
8.) Zenaku
9.) Kioko
10.) Twitch
11,) Abyss
12.) Kamui
13.) Seraphim
As you can see. I have no number one. I have yet to find a person who is the best, for one person I think is great will the next time literally bombs... I'll not pick a 'best' zoner because nobody fits the criteria. Everybody has their best parts, and their worst. Nobody is perfect...
As for some people. I'd rather see more zoning, then OOCing... I'm serious. Bocchiere is a big one. I'm guilty of it quite a bit (note why my name is not there, among other reasons)... I think people could have more potential if they focused less on the technical aspects of everything... and more so on the actual zoning. Of course... that's not saying anything against grammar. I'd prefer to see people use great grammar. Not saying I'm perfect... no. I'm quite capable of seeing that I make many mistakes, nonetheless...
Regardless, that is my list so far... Not that it will be subject to change...