That was a really annoying time when I considering portable soudproof genset.
My experience is that people want (a) easy and (b) cheap.so I'll focus on portable units.
Where are you going to store your generator set up the genset
to use it? Remember, it may be severe weather so, where could you put it to keep it safe and be able to refuel it easily? If you're using power cords, will they be dry and as far out of the way as possible?
Small generators (less than 5500 watts) can only do so much. If you overload the unit and damage it, you won't have any power at all. So be smart! Portable units are made up to almost 20k watts but they're not for people on budgets.
The bottom line is to add up the load (watts) you plan to connect and size your generator at least 25% higher. When motors like the compressor in the refrigerator start up there is a sudden draw of power higher than the normal running load and you want to compensate for that.
Small appliances will have the wattage marked on them. Lighting circuits will be less than 1200 watts each. Water heater is 4500 watts alone.
Also,you'll truly get what you pay for...unless you buy from one of those guys selling from the back of their pick-up truck (don't do that). Don't wait till the last minute or you'll be stuck with whatever is left in the stores.
Oh, and the "trick" with connecting the generator to the dryer outlet to backfeed the house? DON'T YOU DARE!! It will result in damage and/or injury...
Hope that helped a little...sorry it's so wordy