From experience with using all of the above BitTorrent clients,
I found different options and features in each of them.
For a long time I only used BitComet, it was the best until uTorrent came along.
But now the latest versions of BitComet are bloated with useless features and ad banners.
BitComet still has something that uTorrent doesn't have, better DHT support.
BitComet has the best DHT support if you are downloading a torrent with no peers or the tracker
is off line then BitComet sometimes can still download it whereas uTorrent can't.
uTorrent is my choice. It's simply the best!!