Without a doubt electric. you just can't beat the think, rich tones you get from blues guitars, or the heavy distortion for metal. You also tend to get much better shapes and designs from electrics, whereas with acoustics generally have one basic shap, with the possibility of a cut-away. Plus, there are so many ways to customize your electric guitar to make it your own (e.g. Custom artwork, your own pick-up selection, body / headstock shape etc.) I'm not saying i have anything against acoustics (they can also sound really nice) but i just prefer electrics.
Plus when it comes to playability, the action that an acoustic has to offer is usualy very stiff, only good for chords and not much else, whereas with and electric the action is a lot smoother, you don't need to press sown as hard, and generally much easier to play. Plus, as acoustics usually come with thickr necks, its harder to slide your hand up and down it (excuse the innuendo).
However, acoustics still have a very nice charming sound to them, calming and peaceful, especially from a well tuned 12-string. I always enjoyed playing my dad's various acoutics when i was younger and still do. But there just isn't anywhere near as much to do with an acoustic as there is to do with an electric, so for that, I'd say I prefer Electrics.
[TL;DR Version] - It's just apples and oranges, They are both good at different things, and it really comes down to a matter of opinion.
