Deluge
I want to start out by saying I'm very impressed with the progress made since the first version of Deluge. I remember not being able to open torrents from Firefox. Now, it has replaced Azureus as favorite bittorrent client on GNU/Linux. It's only missing two things that are important to me.
1. Whenever I minimize Deluge to the system tray, and then try to restore it, the window appears in the top left corner of the screen by default instead of its last position before sent to the tray.
2. There is no maximum current downloads option. I usually have a lot of torrents in queue, but only two at a time being downloaded so I can guarantee the important ones finish first. (this feature is probably being worked on, but I thought I would mention it just in case)
Thanks again for this great client, and keep up the good work!