I drive a Gator TX at work. It has a Kawasaki in it. When I got it, less than 60 hours were showing on the meter. I can only guess if the initial service was done, but probably not. When it hit 100 hours, I told my supervisor to get it into the shop for service. I'm not supposed to due to stupid union rules, but I checked the oil every day. I reminded my super at least once a week. I kid you not, but finally at over 500 hours it had it's first oil change. I may have added a quart over the course of those 400 hours. Now at nearly 800 hours, it still doesn't smoke or even smell of burnt oil, nor does it make any funny noises. I wrote that motor off a long time ago thinking it would grenade at any moment, but it keeps going.
I own an early 80's model Snapper garden tractor with a Kohler 18hp Magnum. It has a little over 1,000 hours on it. Still going strong with normal maintenance. The only problems I've had were a bad fuel pump and bushing in the starter.
I also own a 70's model Snapper tractor that had a 16hp B&S in it. The engine has been repurposed onto another piece of equipment. I'm guesstimating around 1,500 hours on it. Could be less, but could be a lot more judging by the condition of the tractor. It uses a little oil, no smoke, but just enough that sometimes you can smell it, and the oil level will drop a little on the dip stick after a few hours of use.
I don't think any of you here would argue the B&S is 3rd on this list, but I would list the Kohler as 2nd and the Kawasaki as 1st simply for the reason the Kawasaki will probably be a little quieter and smoother. But, you can get a lemon from any of them.