The B&S engine is a homeowner engine pure and simple. It is nothing more than the old Intek engine with a fancier air filter, fuel filter, and oil filter. It is definitely not a commercial grade engine despite what B&S tries to tell people. I would not want to have to worry about break downs at inopportune moments.
The Kohler engine you list was their 25 hp Command until this year. Now, under the new and more accurate rating system (J1995), it is rated at 22.5 HP. It is still the same engine and real world HP it always was, and will do the same job. Only the way it is rated has changed. I had that engine until about a month ago. It ran my 60" 7 iron deck with no problem.
The Kawi you have listed is the former 29 HP engine, which as you noted is now 25.5 HP. Still the exact same engine and power as well, and like the Kohler is now rated under the new system, and that would be my first choice, followed by the Kohler. I will never buy anything with the BS Pro Turf series engine if I can help it. The Vangaurd engine is another story, and would be right at the top of my picks if given the option.