Voted for Crystal, but in hindsight, I would've probably liked to vote for Red. Nonetheless, Crystal has all the improvements of the Metal Gen (night/day cycle, phone, Special Attack/Defense being two separate stats, two regions in one game, breeding), but it also has a few new side benefits, like puzzles in the Ruins of Alph and kindly having Suicune face us so we don't have to chase after three Legendary Gerbils all over the Pokemon world at that point.
On the other hand, Red was part of the original stuff and is therefore cool in its own right on top of having amusing sprites and awesome glitches all over the place.