I used to refuse to play Monty because his UA and first UU seemed like a rip-off to me, but now with the synergy with the honor track I will try him soon.
I am not likely to play the Arabs until I've played the others, not really sure why, just not a big fan of their combo, although I can see how it could work.
I vary it up, trying them all at least once, but occasionally go back to Nebby, Alexander, Catherine, and Washington. (Washington isn't top-tier, but is good; people don't give him enough credit on here. Certainly better relative to other civs than America in Civ3 or Civ4 was relative to the other civs. +1 sight for all land units is actually very nice for finding goody huts especially, but also for fighting wars and finding city-states easier.)