I grabbed a piece of MDF for the top of my control panel (which is getting a nice CP Overlay from mamemarquees.com) and I really like this stuff. It would make a nice painted surface.
I ended up going with a good grade particle board for everything else as I am laminating my cabinet and from with the guy at a large millworks company told me, he said that there is a reason that laminated countertops use particleboard and not MDF. He said that the glue used to put the two together holds better on the slightly (very slightly) textured surface of the particle board and should yield a perfectly even laying of the laminate. He said that MDF is nicer for painted items, but if you don't do the glue exactly right, it will get wavey, and the glue doesn't hold well to the top layers of the MDF and will tend to peel over time. I don't know how long "over time" is, but it makes since that laminate and particle board go well together or they wouldn't make countertops that way.
If you go with MDF, which again, for painted application I highly recommend it over anything else, be sure to research the screws you are going to use to hold it all together. I have heard that there are right and wrong screws to use with MDF.
Spend the extra could of bucks and get MDF.
Good luck!