A good all round machine that will handle just about anything is a Honda powered gx390 with interpump delivering 21 liters a minute
You get variations on this set up ie loncin engines but I'd go for Honda and ws202 pump as both are bullet proof and reliable with this you will need a header tank as you can't draw direct from the mains supply - wheelie bin is a good choice
Talk to= Rutland pumps - ac pressure washers - Qwashers - I have used all 3 over the years and all have been great for service and advice
Darran