Crusader Kings 2 is awesome, at least if you can get past the difficulty curve. I mean, how many games have killing your own kids as a valid gameplay strategy? And it never gets old to repeatedly assassinate the Byzantine Emperor and watch his Empire fall apart in a long war of succession (and secession). But the game is kinda brutal at first and the tutorial, while decent doesn't begin to cover the mechanics. I had to fail a bunch of times before I managed to get a kingdom rolling. A great game, but you need to be in it for the long haul. If you're just looking to jump in and win games on the fast, it might be a poor choice.
Warlock is a good game. Well, that's not quite true - it's more like half a game. And that half is good, no mistake there. Most of that half is reskinned Civilization 5, but that's not necessarily a bad thing. However, the game is totally focused on combat and lacks meaningful empire building, tech advancement and all that good stuff that I personally love. Also, not much variety to it. You can see everything the game has to offer in a single playthrough. If you can get it really cheap (say, under $10), it might be nice for a quick fix, but don't expect much from it.
I haven't played CK1, but from what I've read CK2 is an improvement in almost every regard, so I'd stick with that...