Golf courses generally use trailing mowers pulled by a tractor.

If money's no object go for the best, a category which would include John Deere.

I have a 18 HP. Craftsman with a Kohler engine which has been serving me very well for several years now. I'm not too familiar with the JD but a couple of things to look for are a heavy duty motor with an automotive spin-off type oil filter and a cast iron front axle - the most common failure point on mowers with stamped steel axles.