Vanilla + Bukkit Survival Server
UK based true vanilla server in survival mode. State of the art 24/7 server with a high speed 100Mbit connection which means no lag.
Much of the world is preloaded which means the server doesn't need to generate terrain when you're exploring, again meaning less lag!
Fair, non abusive admins with a voting system. Bans can be appealed and may not be permanent.
The server is never reset, so what you build stays forever.