Yeah, I played Potion Explosion once, and I was amused at its homage to match-3 games. But there is some tactical thought in choosing the correct marble, so I can appreciate that.
And yeah, I did buy it.
I'm on the fence on Colt Express. Mostly because I've heard good things about it, but I've never played. And I'm not sure how the game is laid out to determine if it is app-worthy or not.
I briefly played a little bit of Jaipur. So far, the interface is pretty good. I even figured out how to manipulate the pieces even though I skipped the tutorial. But I already knew the rules.