lol Azureus is actually considered the swiss army knife of BitTorrent clients, so if you find that too limited, you are pretty much screwed. Did you check out all the plugins available for it? uTorrent is the light****** client. A bit limited compared to Azureus, but uses very few resources which is why many prefer it.

Haven't tried 4.12.11/14 but since it's pre 4.13 it should be OK.