I just bought one, and I did a deep dive before I did.
First thing - measure the surge current of things you want to run. For example I have a portable AC that uses about 1000W when running - but to start it pulls over 17.5A briefly or closer to 2200 watts. Make sure you get something that can handle your surge load.
Once you have the loads download the user manual and find out the max allowable power in the "eco" mode. There isn't much point in getting a inverter type if you can't run it in eco mode, and most of the suitcase generators have very low eco mode power. I was looking at a WEN suitcase generator and it was I think 2500W peak, but max in echo was 750 watts. So in my case, if I wanted to run my AC unit It would be running full out constantly at 3600 RPM, and never idle down negating the point of the inverter in general.
The suitcase ones are quieter (enclosed) but I read some issues with them getting hot if run with heavy loads. Since I live in the deep south and wanted a little more current in Eco mode anyway, I got a open frame WEN - 4000 Watt peak, 3500 Watts running, and I believe 2400 Watts in eco mode - going from memory. At the time it was the cheapest generator of any type on Amazon at
The suitcase generators are all mostly copies of a Yamaha design. The frame types are mostly copies of Honda designs. So you can really buy a Yamaha, a Honda, or a Chinese copy. The Chinese copies are 1/3 the cost. Everything I read said if your going to use it regularly, get a Honda or Yamaha. If your getting a copy, even though they look the same the QC isn't - most recommended Champion (3 year warranty) or WEN (2 year warranty). The WEN was pretty distant 2nd in the reviews but was still pretty good and better than most other brands - if you can actually believe reviews anymore.
I bought the WEN. It was $200 less than the Champion, and mine is pretty much for emergency use only, so I figured it was good enough.
Edit - almost forgot - if you don't already have you need to budget for some good extension cords and good jerry can's - and possibly spare parts. I am sort of OCD on spare parts - I have a coil, carb, recoil starter, spark plug and fuel line in my "spare parts" stash, even though the thing is brand new. I figured I would buy the parts now while there available and cheap. I think everything was like $75.