What are some alternatives?
When comparing Deluge and rTorrent, you can also consider the following products
qBittorrent - Lightweight and open source torrent client that runs on all major platforms.
Transmission - Transmission has the features you expect in a BitTorrent client: encryption, a web-based interface...
BitTorrent - BitTorrent is a peer-to-peer program developed by Bram Cohen and BitTorrent, Inc.
Tixati - Tixati is a peer-to-peer file sharing program that uses the popular BitTorrent protocol.
Vuze - Vuze is a free BitTorrent client used to transfer files via the BitTorrent protocol.
WebTorrent Desktop - Stream torrents