Deluge
I installed Deluge for the first time as an alternative to utorrent and qbittorrent on my pc windows, but are not present many important features.
missing:
minimization (not closing) in the notification area
the extensions renaming of temporary file
the sequential download of file's segment
a simple torrent search function (local or web)
also some extensions must be compiled with python, but most people do not know what it is or not they are capable
it is unfortunate, because it seems a good program