All torrent clients are pretty much the same it really does only depend only on seeders.
They all download torrents and use pretty much the same methods, it all depends on seeders. It also depends on your internet subscription (pay more = faster max speed).
You can download the same torrent in different clients and you will pretty much get the same exact speed.
I did vote for utorrent however because it has a very minimalistic and straight forward interface but gets the job done (And if you wish to fine tune any settings you have the option to). It is also a very small program and comes with exactly what you need, a torrent client, without any extra shit-ware.
I used to use Vuze back when it was Azureus, but since then they have made many changes and turned it into a torrent client/video player/a bunch of extra shit.
It's nice that it comes bundled with all of those extra things, but I prefer other programs to do those tasks and don't need all of the extra bloat.
I've used utorrent for years and I love how it is a small, powerful program that has all of the features a torrent program should without any extra booshyt.
http://www.utorrent.com/