Honestly my advice is only that it runs on the fuel that you can keep on hand and is moveable (as in lift into a truck) with two men. Several I looked at were odd shaped and too heavy to move for home use.  
Multi fuel might be a plus but I use diesel because its more stable, not a fire hazard and every 6mo i can empty it into my truck. 

As soon as you get it, use it so you know how.

Shut power off to the house and use it for a day. This may sound like overkill… but at my church, ive heard countless stories of people not being able to use their emergency generator for whatever reason and when I show up, it’s obvious its never been on before. 
Fire it up once or twice a year and make sure wife/kids watch you do it. 

Just put that chore on the calendar. 
🍻🧡👊🏻🥩