Why wear a blue shirt, when there's yellow shirts available?
In terms of actual features, Transmission is more lightweight. It doesn't support super-seeding, broadcatching, native SOCKS support and doesn't have built-in search engine integration.
This is true but for me this is a disadvantage. qBitTorrent allows to fine-tune a lot of settings. Not as many as Tixati but still.
If you want to go that route you might as well use Deluge, which is built on the same libtorrent library, has a proper daemon-client architecture with fully featured native clients for all major platforms.