Having finished Spelunky 2 I've found myself enjoying its mechanics to quite a degree. While it might be weird to think about, Spelunky 2 improves on everything Spelunky HD does and more. Not only are the controls more responsive, the art style has been refined and the level-chunk design improved vastly. Going back to HD after having played 2 is a shock, to be honest. I finished it after about 104 hours, but I'm sure your mileage will vary a lot. Still, there's more content to be had, so I'll still be going back.

If you've never played Spelunky this is a good starting point, however it's more punishing straight out of the gate, so be prepared for a proper challenge.