I generally just use a knife for most meals, but FP's are wonderful for when I'm entertaining. I also like to slice a week's worth of onions or bell peppers and keep them in the fridge to save time on weekdays. I have 2 - a basic 3-cup Kitchenaid chopper for daily use, and an 11-cup Cuisinart for when I need anything special done.
Think carefully about what you want to use it for - for general chopping/grating of small quantities, then a basic model will suffice. If you want to julienne, chip, slice very thinly (1mm) or thickly (up to 8mm), then you will need a larger model with speciality blades.
You will generally get what you pay for with Food Processors - I went through several cheap ones before I came to my senses and bought a good one. Things to consider are:
* Feed tube size: The bigger the better because that saves you spending time chopping things up with a knife just to be able to get them in the processor!
* Availability of other accessories, such as special discs and blades.
* Power - a weak motor won't cope.
* Ease of use and clean-up: If it's a pain to use or clean, then it won't get used...
The two best brand names for home use are Kitchenaid and Cuisinart, both are around the same price range. I think that Cuisinart makes models with the widest feed tubes, and both allow you to buy additional discs.
My final tip is to keep it out and on the counter, if you possibly can. Food Processors that have to be wrestled out of cupboards rarely get used!
Paint.