Recs.
Updated
qBittorrent aims to provide a Free Software alternative to µtorrent with a polished user interface and an abundance of features.
SpecsUpdate
Pros
Pro Full-featured
qBittorrent covers basics such as Prioritization, Selective Downloading, DHT, PEX, LPD and Magnet URIs as well as Broadcatching, Sequential downloading and Search. It includes MSE/PE for security. It has graphical, web and command line interfaces. Has UPnP, NAT-PMP, NAT traversal for automatic router configuration. Has UDP tracker and µTP data transfer protocol support. Even covers Tracker Exchange, IPv6, web seeding, Embedded tracker, Super-seeding and proxy servers.
Pro Allows share ratio limiting
Can configure to what ratio (amount uploaded/amount uploaded) the torrent should be seeded. You can also configure on whether you want them to be paused or removed after this.
May also set this directly in the ~/.config/qBittorrent/qBittorrent.conf
:
[Preferences]
Bittorrent\MaxRatio=2.5
Bittorrent\MaxRatioAction=0 # 0=Pause, 1=Remove

Pro Can be run as a background service on Linux
You can set up qbittorrent-nox to run in the background automatically each time you start your computer. Access to downloads is through the web interface.
Cons
Con Constant IO error
If there is no free space, you're going to have infinite amounts of io error notifications every couple of seconds.

Con Missing Files error on completed downloads
This error occurs usually on Linux. If you have a completed torrent and qbittorrent is restarted, it will show that those files are missing. Bug has also been created.
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