µTorrent 3.4.1.30686 Beta + Portable | 1.4/2.8 Mb
µTorrent is one of the most popular BitTorrent clients, with plenty of features such as bandwidth prioritization, RSS auto-downloading, scheduling and Mainline DHT (which is compatible with BitComet, another well-known BitTorrent client), Protocol Encryption joint specification (used also by Azureus, BitComet) and peer exchange.