When I started using Ubuntu in the beginning of 2005 one of my criteria for being able to switch was a good working torrent client. After testing several clients I decided on Ktorrent as my client.
The choice for Ktorrent was really not that hard looking at the great features that Ktorrent has. Of which the bandwidth scheduler is probably the coolest. This allows me to schedule the seeding part to the hours that the network is not being used.
For more information please read my article on Bright Hub by clicking the link below.