I guess most people will say 1planhost.com! I've tried them several months ago and gotta say they indeed are rock solid reliable but found out that download speed is somewhat limited. Around 70KB to 80KB/s.
So for reliability and speed, I would personaly recommend databasemart.com
They have really good support, one the most important features.
Been with them for almost 3months and only have good things to say about them.