I'm installing two 14KW Kohler RESL models and one 30KW Kohler RESA model. The customers supplied the generators bought online from a internet seller. I also am working on a 17KW Generac for a customer.
The Kohler installations went smooth and the transfer equipment was OK. I like the 14KW kohler model.
I was told that Generac is inferior to others in the quality of the parts used and that down the line it will cost to replace the parts.
I needed to get a authorized dealer to do the start-up and provide the customer with a service agreement, so that will be key to your decision on who is in your area to do this.
I heard the GE 15kw is a nice unit.

shortcircuit