Of course Deluge, written in python can not compare to uTorrent's tightly optimized C++ code. Transmission is better, but its back-end (libTransmission) is not as well optimized as libtorrent-rasterbar. Any C++ client based on rasterbar such as qBittorrent should offer similar performance to uTorrent.
If you don't require streaming, older uTorrect clients are still your best option. If you do, it IS possible to install the recent version of uTorrect without any external adware and to disable all of the banner ads.[1]
[1] http://forum.utorrent.com/topic/81421-321-how-to-turn-off-ad...