I haven't tried all that many from the list. Azureus gets my vote too.
It is more advanced than the simplistic (yet effective) official BitTorrent client and the new versions feature some nifty little additions that I like (for example the Swarm tab is cool).
It also has a fairly intuitive interface.
One of the problems though is that because it isn't as simple as the official client, it doesn't do very good if I try to run at the same time as LW.

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

"Raise your can of Beer on high
And seal your fate forever
Our best years have passed us by
The Golden Age Of Leather"
-Blue Öyster Cult-