The pioneers you will want to use the dash kit because they have a slightly bigger gap around the dash than kenwoods or alpines. Alpines are going to be the fastest choice but going to be much more expensive. Kenwoods have a slower interface however have a grear bluetooth setup and garmin gps.
600 is going to be a tight budget to get everything you want here is the cheapest one that I would recommend.
Kenwood DNX5180 Navigation receiver at Crutchfield.com
Or you can get an older kenwood 6140 for cheap.