Solar is great, but if you want to run A/C, or have string of cloudy days, it's good to have a generator. You can even use just a generator without solar. A generator will charge your batteries and give you power off-grid.
This one isn't much of a decision, you should be getting an inverter generator. Normal, non-inverter generators are typically used in construction. They're far louder and produce less pure electricity, so they're not great for electronics. All the generators we list are inverter generators
Generators come in all sizes - typically anywhere from 1,000W (watts) all the way to 7,000W.
An RV A/C takes ~3,000W to start and 1,500 watts while running, but most other electronics will take 1,500 or less. ~2,000W is generally good for anything but A/C, but you'll need 3,000+ if you want A/C.
If you only need the generator to charge your batteries, and have an inverter that's powerful to run the electronics you need, you can get away with something as small as 1,000W to charge your batteries.
Higher wattage generators are going to be larger and heavier, so you'll need to factor that in as well. You can get two smaller (2,000W) generators and run them in parallel so each one is easier to move than a larger 4,000W
Generators usually list the "surge" watts, but you should be using the "rated" watts instead. Also factor in that generators don't work at 100% efficiency at high altitude. At 5,500 feet, they run at ~80% efficiency (meaning a 2,000W generator will provide 1,600W)
Some generators can run off both gas and propane. Running on propane is less efficient and more expensive, but propane is something you'll usually have if you're in an RV. Sometimes it's nice to have the option, but most generators are gas-only.
The two brands people trust most, by far, are Honda and Yamaha, BUT they cost about double what the other brands cost. There are other good brands out there with good reviews, but on average, they are probably not as reliable. The question is, are they at least 50% as reliable? It depends on who you ask, but plenty of boondockers get by just fine with the other brands.