http://www.wow-europe.com/en/serverstatus/ - European servers.
There are descriptions of the different types of servers
here.
It's up to you which type you chose to play but if you start on a PvP server you may find yourself getting annoyed with the amount of high level tossers who think it's fun to gank noobs and lowbies. Also take into consideration the faction ratios. On all servers you will find that the Alliance outnumber the Horde by at least 2:1 (2 Alliance to 1 Horde) on my server (Aggramar), the ratio is 3:1. Fortunately we Horde don't care much that we're outnumbered as the Battlegrounds have proved that we are more skilled. When the numbers are even, Alliance don't stand a chance.
On most 'English' servers you will find alot of Spanish, Russian and Scandanavian players as they don't have their own servers like the French and Germans do. Most of the time this isn't a problem but recently, on the Agamaggan (sp?) server, the Spanish population became a problem and consequently nearly the entire English population transfered to a new realm.