Go with any generator that has a Kubota motor. I have the 8 kw Power-Tech and was glad to see that 3 cylinder Kubota for power.
I use work for a equipment & golf course company. We had mowers all with Kubota's that ran full throttle (about 2400 RPM) 12-14 hours a day 6 to 7 days a week 8 months of the year. The only maintenance was a regular oil change. Most of the machines would rack up about 3000 + hours a year and we would dump the machine after about 3-4 years usually because the machine was falling apart, but that motor was still perfect. Just a great motor that you will never have to worry about.
2003 28' Show Hauler Motorhome on a 1995 FL 120
www.showhauler.com