I purchased a pressure washer last summer, did quite a bit of research and talking to suppliers and rental firms. I was told to get one with a Honda engine and a belt driven pump if possible and avoid radial pumps. I was told that there are many grades of pumps, with CAT being one of the better (and more expensive) and price pretty much goes up with expected life. I ended up getting a Northern Tool unit with 5.5 Honda engine and direct connect General Pump 3gmp/2500 psi and interchangeable nozzles. It has served me well, cleaned the deck, house, tractor, under side of the vehicles, cleaned the down sprout drains using special tip the connects onto hose directly, then you feed the hose into the pipe, blasted hornet nests from under the deck and bird nest from over bathroom window. It will remove paint off vehicles (purposely on our 89 Ford PU), masonary, and probably everything else. Avoid small electric units, neighbor got one to clean his deck (12x15) and it blew the pump within 2 hours of work. Took it back and was they weren't surprised, most others had come back with less than 25 hours of use.
