The best replacement for rtorrent is deluge.

The best alternatives to rtorrent are rated as following:
★★★★★  deluge
★★★★★  utorrent
★★★  ctorrent
★★★  transmission
★★★  rutorrent
★★  libtorrent
★★  aria2
★★  qbittorrent
★  transmission-cli
★  torrentflux
  transmission-daemon

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Speaking about rtorrent, one probably shouldn't forget about magnet links.

Other search terms related to rtorrent and their ratings are:
★★★★★ magnet links
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Google Trends

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