id recommend olymp server. Ive played both servers.
Camelot is fun for 2-3 months then gets boring, lag was pretty bad and server wasnt very stable.Lag may be because i live in europ and servers in USA. But lvling was fast and killing bosses was pretty easy and fun.
Olymp server is more of a long term server. Lvling is harder, exp lower.
No lag, and server is very stable.