Well if we're all breaking the number rule....
Underthemoon - The BEST roleplayer in Planeshift. No one can devise a twisty turny and keep-you-guessing plot like Underthemoon, and no one can pull it off. He does amazing things with roleplays, he makes them enjoyable and can usually get lots of people involved. He is one of my... Mentors, for lack of a better word.
Zhai - My most prized member ever in the Rangers of Yliakum, I remember getting Zhai (ICly) from Xillix, who'd referred her to Farren and the Rangers. Zhai was fresh and new and had great potential for RPing, and it grew, eventually leading into the Dwarvesbane-Dwarven Star war, where Zhai's RP became superb and finely honed. I really wish I could say I had more to do with her development, but I do not think I had much to do with it beyond the initial RPing.
Duraza - Duraza is likely just under UtM for his plots. I've seen people accuse him of 'godmoding', but then, I've seen the same people call other players 'godmoders' for doing the same things (or in some cases, worse). However, Duraza is very good at creating interesting plotlines that, while people may find them the same over and over, that is PART of the plot. You'll see his genius someday, non-believers. All in all, I find Duraza's characters to be interesting and find him fun to RP with in general.
Lolitra - Lolitra is a very nice person, never aims to hurt anyone OOCly or anything, and in general tries to bring fun to everyone with her RPs. She accomplishes for the most part by creating smooth, mostly stress-free, and creative RPs, and she manages to bring in many groups, even the small ones like my own Rangers of Yliakum.
Saelan - I haven't known Saelan as long as I've known the previous people on the list, but in a short time he has become one of my greatest RP allies in Planeshift. His RP style seems similar to my own, quite compatible to say the least, and his character(s) are interesting and fun. He seems to be budding in the RP plot creation area, and while he has not yet attained a status of fame like UtM, or even like Duraza, he certainly has the potential. He is new(er) after all, compared to the other great RP plotters. Recently, his character and my character have become sort of like best friends, and thus, RPing with him is a blast, fun and exciting.
Suno Regin - If you do not recognize him by this name, you may recognize Mitaki, but this was one of my earliest RP friends, back before Farren was who he is today, back when Farren used two longswords, not two shortswords. Ever since, he has always been my friend, even when he didn't play PS, and when he came back, he might not have been the BEST RPer, but he put out the effort, and improved all the time, and became much better. He is one of my favorites because he is fun to RP with.
Proglin - I tend to forget him in these kinds of things, but I believe he was not only a great RPer, but he brought fun to everyone with his RPs. They weren't plots and such, but were a different sort of RP.
Kaerli - While Kaerli may seem to have trouble RPing realistically sometimes, he has a few problems that I understand and aren't necessarily his fault. People seem to think badly of him, and it isn't truly fair. I cannot explain why he might have certain trouble with things, it is not my place to do so, and he may personally disagree with my opinions on it. Either way, despite whether or not he is a 'good' RPer, he is still one of my favorites because I can always depend on him to make my own RP experience more fun and most importantly... Less lonely.
Valiki, Eretelien, Nalelack, etc. (Waddling Yulbars, basically) - This little gang, even when they're not getting themselves hunted by evil people, are fun to RP with simply because of the nature of their characters and guild. I can't say much else about them, and don't think I really need to.
Note: If you're my friend and I didn't add you... It simply means your name didn't pop up in my mind while I was typing this. Nothing more. It doesn't mean you suck at RP... It might, but not necessarily. Don't fret over it, i will likely add more to my list if I think of any big ones I missed. Oh, and thank you for you two who added me
I mostly didn't add you to mine cause I haven't thought of a good reason to type up yet, but I do enjoy RPing with you the few times we meet Gag, and Gharan, I'm not sure if I've RPed with you in a long time o.O
EDIT: Oh crap, forgot one that I meant to add....
Xillix - Xillix, back when he RPed, played a slightly fanatical Laanx high priestess person thing that wore a jester hat and was funky looking. But Xillix promoted RP and RPed very well, also helping newbs [not to be confused with n00bs] learn to play the game in a roleplayed fashion. I donated all of my money to the Vespers of Laanx (that's why my character is broke these days) and was at one time a member of the guild. In the end, Xillix's RP affected me I think, ad perhaps influenced the way I RP.