Back in the MTW days "Kill the Turks" used to be my mantra in my Byzantine and Egyptian games. They were compact, aggressive, and with nowhere to expand except into Byz/Egypt.
Nowadays, at least in my Byz games Turks seem to be content with grabbing rebel settlements aand are generally pretty docile until the mid-game. In fact, Venice has invariably been my #1 enemy game after game after game with Hungarians as a close second.

I'm curious whether or not other Byz players have experienced the same thing, i.e. the main threat to the Byz Empire coming from the West rather than the East.