I have used Sony, Nikon and Canon. they're all soooo good, but since i only have Canon S2IS for 6 yrs and couldn't afford for more, the best thing i can now is to take its every inches for granted lol and also, i'm used to it, so it's more about the feeling, like shutter sound, weigh,... ya.. they're all different
Nikon for me, after a long hesitating moment between Nikon, Canon and Pentax. Nikon won with the lens choice, AF performance, performance in low light conditions. There wasn't any serious concurrent in the Sony lineup for an "expert" camera at the time. And so I chose the Nikon D7000 (BUT the D7000 features a Sony made sensor, hehe ) (and I use a Minolta analog camera, so... )
I really like the set up of my Canon. (but I think that's more-so 'cause I'm used to it). I've used Nikon and I like them as well, and I've used a SONY, which wasn't bad, I actually liked it quite a bit also. :< They all have their good qualities, and their ahem, not so spectacular aspects (I don't like the way the Nikon I used fit in my hand.)
Canon, although I shoot with a Samsung. Do not recommend. The thing about Samsung, is that their products are great, Really great. Except they always break, or become faulty/dodgy. My old MP3, my old MP4, my camera ( the lens needs manually pulling out with fingers) and my sister's camera. I like Canon because I went to a shop and tried out all the main brands, and it 'felt' the best in my hands. Still have to persuade my parents it is worth the money.