All depends how much you want to spend. I have a gas Generac that's been severely neglected I've had for like 8 years and it fires up every time, works great. I went down the rabbit hole for electric units because I'm sick of the noise, shutting down and restarting between foaming and rinsing.
Basically you ignore PSI and want at least 2 GPM flow rate. Days of reading and watching reviews, sounds like a Kranzle K1322TS is the best you can get electric wise for car detailing without absolutely needing dedicated 20A outlets, they say it can spike past 15A draw with foam cannons but a wider orifice on the cannon should help with that. I plan on getting one at some point. Kranzles are over engineered and built to last with proper maintenance which they design to be easy.