Contrary to what most people will tell you, ignore the PSI ratings. You can get the washer to spray pretty much as much pressure as you need. What you need to focus on is GPM. Water is what cleans.
In the "old" days (pre-2010), the ~5 HP engine/2.x GPM pressure washers sold at Lowes were all but disposable units. They'd last a homeowner a couple of years (3 or 4 if REALLY cared for) and then tank. They cleaned OK, but the pumps would go out because they were direct drive, you couldn't change the oil, and people ran the pumps and engine without running water through it. ALWAYS turn the engine off if you aren't spraying. Back then, the pumps cost as much as the entire unit to replace, so you'd see those things on curbs.
These WILL work OK but the warranty is often short and when they go out, the pumps still cost a bit to replace. Cheaper now than they use to be due to replacements on Amazon (cheap Chinese models), but at least you're not left with a boat anchor. I personally wouldn't buy one, but if your needs are light and you can only spend $500 or less, they are an option.
Most pros will tell you a washer with a 4gpm pump is the minimum for any real work. I think you can get away with a 3.5gpm model, which is what I have. 3.2s are pushing it and they're almost as expensive as the 3.5/4. THIS level is what I recommend.
Brands aren't THAT big a deal, but get one where you can change the oil in the pump (and change it regularly). I'd go with a Kawasaki or Honda motor. My DeWalt from Home Depot (I think they still sell that brand) has a Honda motor and (I think) a Triplex pump. There's another brand, I can't recall the name, that's pretty good. Anyway, Simpson sells pretty much the same thing. One thing I'd keep in mind on brands is the accessories that come with it. I HATED the hose and wand that came with my DeWalt. I finally trashed them and got another hose (Uberflex), a spray gun (Amazon Italian knock-off; I can get a link), and some extensions from Northern Tool.
