Some newer generators have fuel injection. If you live or shelter at higher elevations or want to minimize your fuel use, Fuel Injection might be on your list.
If you value your electronic toys and some modern HVAC systems, check out the Total Harmonic Distortion (THD) less then 6% if I remember is the max you want. Inverters are good at providing good clean power. Few have enough Watts to power a home.
Generac has a printable form to figure out your base and starting load requirements. I'm not a fan of there heavily advertised equipment.