I commission generators and switchgear for a living. Good advice in this thread.
Look at which fuel is going to be hardest to have delivered in an event. Might be tanks full of propane at the fuel company, but no diesel for the trucks. Natural gas is shut off in seismic events, though it is the cheapest. I’ve been partial to diesel.
Always size the tank for the worst case run to fuel consumption. If propane, it must be sized to give the required surface area for vaporization. If NG or propane, keep the fuel piping as straight as possible, size it 50% larger than the stated CFH required. If diesel, install a water separator filter with valves before and after, to allow changing. Keep diesel tanks at 80-90 percent to inhibit condensation on the inner tank wall.
NG or propane are a bit more complicated to operate from the engine side, diesel less so, unless it is Tier 4, and Tier 4 hasn’t overrun the standby market, yet.
As an electrician you can troubleshoot and repair most problems yourself. Our service rate is $125 and hour, my position is $150. At those dealer rates, for a homeowner, those Lowe’s generators are throwaways.
You need enough KVA to start required loads, and enough running KVA to load the engine to 30% minimum. If you can’t maintain that loading, you need to put resistance load on the unit once a year to get to 80-100% load for an hour or so.
Time has shown, in my experience, that every 9-12 years there will be an expense. Unless a lightning strike occurs. Control boards run from a few hundred to a couple thousand. Aftermarket controls are a cheaper option, and work in most cases. Not all sensors are compatible. Always consider parts availability and lead times.
The less complicated the package, the cheaper it is to purchase and run. But a cheap package can cost you a lot of money.
Consider a PTO driven generator, if you have a tractor. A crafty fellow could come up with a generator end, fabricate a coupling, design a voltage regulation system and be set just that quick. Or you could buy one...
Almost all 12 lead generators can be rewired from three phase to single phase. There may be a required change to meters and the voltage regulator, possibly the control board. It’s not always cut and dry, so due diligence prevails.
Manual transfer switches have no controls to fail. An indicating circuit on the line side can alert you when power is restored. ATS switches are subject to surges and lightning strikes. There is a wide variety out there, and a lot of bells and whistles.