I've tried so many.
Favorites:
seedboxes.cc - quick setup, good controls, reasonable speeds. I dropped them for feral since they seemed to be better for the money
feralhosting - probably the best all around hoster. Besides the horrible move fiasco, which is now over, their speed and hard drive space for the money is pretty unmatched.
seedhost.eu - Almost as good as feral with even better hard disk space for the money, although you seem to sacrifice some upload speed so you need to weigh what is most important to you.
superseeder.eu - Good for the money. You can get a dedicated IP and have a ton of control over the box for about $15 a month. Upload speeds aren't as good but they aren't bad.
Support on all of the above was excellent.
Stay away:
seedbox.org.ua - they never once replied to me. Had to get paypal to get my money back. Their speeds look awesome but I question whether they are accepting new users.
seedstuff.ca - cheap overloaded boxes, I got their $10 a month box and it was pretty terrible. The speeds weren't even remotely close to any other vendor I tried. Granted it might be better on their high end boxes but at least stay away from their entry level stuff. Their support was quick to respond and helpful but the slow uploads killed it for me.