i used azureus for a year or two and recently switched over to utorrent. much better... smaller, faster, simpler, and actually had some features azureus didn't like the speed graph and scheduling. well, azureus might of had those, but i never came across them in the myriad of menu options.
what i use depends on what i'm looking for.
i use utorrent for most things. movies, programs, tv shows, etc.
i use emule for individual songs and stuff thats harder to find and get from the various torrent trackers i visit.
i'm sure all of those will be the same speed. i doubt any of them are faster then other programs. it all depends on where you get the file from and your connection. every p2p program i've used (dating from when kazaa was first introduced) has maxxed out my downstream with ease.
I, myself, use limewire for certain files, but I have friends who use emule because Asian oriented sites tend to prefer the program. I think that both programs are similar in speeds. If you really want fast speeds, I think you should use bittorrent.
As for the bittorrent applications, Azureus is a great bittorrent application for advanced users. Although, the addition of Vuze may have been a bit too much because Vuze is really just adding more bulk to a very bulky application. Azureus will consume a large part of your memory while it is open and running. I recently switched to utorrent, and although it does not beat Azureus in the looks category, it is definitely on par with Azureus in the capabilities. Another great thing about utorrent is that the size of the program is ridiculously small, so it is a amazing program to enjoy at very little cost.
Carpo: uuh.... i guess you missed where it specifically mentioned "services like LimeWire and eDonkey."? there's one advantage to the majority of websites where torrents can be aquired over that of any file sharring app. it's those little things called comments, and also the ability to remove the torrent from circulation should something such as a virus be discovered in an associated file. You're also more likely to be able to avoid fake files due to the ability for people to comment on those files.