I recently went through this and got the OG-spec gun. Totally overkill, I wouldn't buy it again but I'd still probably pay up for a swiveling Mosmatic.
Whatever you do I'd definitely get a swiveling one and I'd highly recommend quality quick disconnects. Just pay attention to coupler size to match your pressure washer hose.
I have the OG-Spec Mosmatic gun, wand, 50' Kobrajet pressure hose, 6.5' inlet hose, stainless quick disconnects all around (including the inlet hose) all hooked up to a Active VE52 pressure washer. I paid top dollar but I'm very happy with the setup.
I am deciding which pressure washer I want to go with, and seeing a lot of people praise the Active VE52. Its about 200 on Amazon so not a lot more than the cheaper washers out there. Any thoughts on if the extra expense the extra GPM is worth it? I think I would probably use as is for a little while until I upgrade the hose and gun. I think the Active hose and gun are a bit better than some of the cheaper washers?
I had a cheap karcher for a long time that crapped out on me a while ago. I was happy with it, but also never tried to use it with a foam cannon.