So, friends of mine recommended Crusader Kings 2 to me a couple weeks back, and I have to say, while it has many things in common with Medieval II Total War, I'm finding it far more engrossing than the latter. The Total War series spends a lot of time and development cycles on the tactical maneuvers in individual battles, which I've frankly never found as compelling or interesting as the campaign world itself.
Crusader Kings 2, however, abstracts those combats further, focusing instead on succession law, intra-realm strife, and the politics of the world. As a simple example, you cannot arbitrarily attack someone; you need to put some work behind justifying your attack, however flimsy that justification might be. That is, you need to have a disaffected vassal with a claim on that title that you can press, the enemy needs to be a heretic or pagan (no arbitrarily attacking Catholics!), or you need to send your Chancellor to the province to manufacture a claim by manipulating documents and bribing various vassals.
Most compelling, I think, is the fact that I can honestly say that I've learned a great deal about northern European geography and medieval succession laws that I simply didn't know before. It's kinda cool.