I've never played EU, but I would recommend US. Many players from European servers, especially english speaking ones have came here b/c of the terrible population over there.
If you bought a boxed edition or installed a GOA (European) version, then I don't know of anyway to switch over. You probably have to install. You can install this game from the website at http://www.darkageofcamelot.com/download/
It does not matter where you are, you will get the US version if you do this, but it is a lengthy download.
Sorc and anything with a smidgeon of heals is good. Friar/Paladin could work as well..fairly poor crowd control, but good healing, and eventually bodyguard if you play on a ToA server.
Good luck