Another vote for qBittorrent. I switched to it, after uTorrent started adopting shady practices, such as installing other apps and changing my system settings, without permission.
It [qBittorrent] is ugly as sin and there are also a few hoops to jump through to get rid of OSX's "Allow qBittorrent to accept incoming confections?" alerts. But I've found it rock solid and more reliable than either uTorrent or Transmission
