I have used Kohler engines on many different mowers over 40 years, generators, welders, pumps also, and have found them to be of high quality and need little maintenance.
Every Dixie Chopper I have has a Kohler on it, and all my pressure washers has Honda engines on them.
It all depends on what you know about the engines and how to maintain them.
If you shop around, you can find some good deals on the engine you need or an engine that will operate the machine.