I have an a200 from sony... so its the only camera i can comment on.
the cameras are very similar apart from live view.
The camera itself is good, and fast, its the lens that also determines the quality of the shots dont forget, and the speed of focus etc.
The sigma 18-200 i have i would say is a pretty slow lens. Its good in bright light, sunny days but struggles in low light and even on a cloudy day the lens hunts in and out before focusing.
In contrast to that the 50mm 1.8f i have from sony is great even in the dark and focuses lightning fast, takes great sharp pictures with low noise.
Personally i would say the sony is the better camera out the ones you have listed, but it depends on your overal budget, are you just going to use the kit lens? or are you buying seperate lenses as well? Have you considered looking at buying
second hand? for the price of a sony a330 and lens you could get a better nikon or cannon, or even sony setup
second hand from the classifieds section...