The client I use is ABC. I like it 'cos you can queue your downloads, set upload caps that don't affect your download speed, and set it to automatically stop uploading after a certain amount of time. Very nice.

Most of the stuff I get is from suprnova.org, boxtorrents.com, and animesuki.com. Box Torrents is the best place to get complete anime and manga series because they have rating systems and such. You have to be a member there, but it's worth it.