What are some alternatives?
When comparing qBittorrent and aDownloader, you can also consider the following products
Transmission - Transmission has the features you expect in a BitTorrent client: encryption, a web-based interface...
µTorrent - Looking for a torrent site to download movies, music and more? Choose from top torrent sites like The Pirate Bay, RARBG, 1337X, and dozens more. (October 2019)
Deluge - Deluge is a full-featured BitTorrent client for Linux, Unix and Windows.
BitTorrent - BitTorrent is a peer-to-peer program developed by Bram Cohen and BitTorrent, Inc.
Vuze - Vuze is a free BitTorrent client used to transfer files via the BitTorrent protocol.
FrostWire - Easy to use BitTorrent Client and YouTube Downloader in one, with built-in search and music library.