Generac is the king of the Home Gene world, followed by Kohler and couple others. They are all all about the same and Generac is probably the most consumer friendly. Local code variances aside, you want a Gene that runs off NG vs Petro as you don't have to fuck with fueling it, presumes you are residentials and have constant NG. You want it placed 10ft from the house for ventilation purposes. You will need a plumber and the local gas company to collaborate on the install, very easy and happens all the time. You might need a bigger gas meter, not a big deal, they will swap it. You may also need some black pipe and the Gas Company and or Plumber will handle that. W.r.t whole home Gene...you want an Auto Transfer Switch so it kicks in automagically and there are no wires to connect, which means no opening to the outside of house.
https://www.generac.com/all-products/generators/home-backup-generators/guardian-series/22kw-7043-whole-house-switch-wifi-enabled
Lead Time: get ready to wait. Generac and most others were already experiencing manufacturing delays due to Covid 19, then this summers storms impacted the timeline as well as everyone up here ordered the after the August storms.Expect a few months.
I look at it as insurance and in investment in my property. a whole house project (on Long Island) can run between $8k and $20k depending in size, complexity of install requirements ,etc. the units themselves are pretty standard w.r.t cost, its the install that gets you.