There's not much risk involved in this decision - you can always export your subscriptions and settings and import then into another server if your original choice doesn't work out.
The servers are listed in order of how fast they are - look for ones with a rocket or lightning icon.
Stability is a rough measure of how organized the admin team is and how much support they have, not uptime.
Newbie friendly servers have set up some starter-packs to help you find interesting communities more easily.
Age is how long the server has been online for. Generally older ones are more likely to be around for the long term.
The language of the server only matters when need to communicate with the admins.
Click 'more' on a server to read a longer description of it.
PieFed