I've been playing on Reni so far because Artemis seems really crowded (and cuz I like words with "i" on the end). I'm only lvl19 (second character in a week, first was noob fail >_<) atm, but I think Reni is fun so far. There aren't a lot of people running around stealing your mobs, but when you need help and you zone chat, there's always someone who has no problem helping or partying you. As for a guild, I found one almost right away when I asked in zone chat around lvl15 (first character).
I found Reni to be very friendly, fun, and helpful

To all those people who were complaining about world chat, trolls will be trolls, and they will be there even on the "best" server. Stressing over it takes away from the fun of playing the game.