In a previous life, I used to repair standby and portable generators. The number 1 and 2 brands were Onan and Kohler. I believe Onan was bought by Caterpillar.
Generacs were disliked for two reasons. First, they were 2 pole machines which meant they rotated at 3600 rpm instead of 1800 rpm. Higher speeds equals more engine noise and more vibration and potentially shorter mechanical life.
Second, they used epoxied sealed plug in "blobs" for control units i.e. voltage regulators and such. Each model apparantly used unique blobs with no interchangebility. That goes back to the previous comment about needing to stock too many spare parts.
I will like to correct one mistake here real quick the Onan is broughted by Cummins engine company not the Caterpiller Company.
let you know the correction there
as what other reflect what they saying about Generarc Generators i do agree with them.
I have few issuse with them as well the part network is very poor and majorty of items is not really standard parts at all that why i shy away from that company
most of my generator sale is kinda like pretty well equal Onan [ Cummins company ], Caterpillar ,Kohler , but few other as well if the comuster request it
My typical choice for resdental area is a slow speed [ 1800 rpm units ] useally 12-18 Kw range [ that will be serve most home load easly unless supersized home that diffrent ]
for fuel choice it depending on the area majorty of small units genrally spec'ed for Natural gas or LPG but diesel units as well but some local area may not allow diesel unit at all for other reason so just check all angle for this
my home i have 20 KW diesel unit with subbase fuel tank that will useally last me about 2 days of full running time but half load it will get 3 1/2 days
then again i will mention that the Generarc generators is " cheap " to me