Which of the two is the better buy?

Craftsman 5 hp for $298.88
-----------or------------
Craftsman 6.5 hp for $419.88

General use would be for washing the deck, cars, siding...nothing major.

Do you recommend any other brand names?

i wouldn't look at the HP rating of the engine as much as the pressure rating...for the jobs you've describeg a pressure washer that puts out between 1500-2000 PSI would be sufficient