Gibson Les Paul for me, without discussion.
I guess it's a really personal thing, it's hard to precise why I would prefer it over other great guitars, but it's just the whole feel, the whole thickness and the volume of the tone and the sound, the weight, the neck... lol, everything about it. I find the necks of Fender and the likes too thick for one, and I often find too much treble in much of the other brands. But that's in my humble opinion.
As for acoustic guitars, I'm a bit more varied, there's a lot of great acoustic guitars and extremely varied prices and sounds. Sometimes one guitar is really good for ceratain songs while others might sound completely different. I've had quite a few different brands of acoustic/semi-acoustic guitars but I can't say there's one that's definately my fave.