Its been my findings over the years the kohlers are the least hardy of semi modern-modern lawn equipment.
Kohlers run forever untill they are shut off, abandoned for years, then forced to resurect.
Now briggs on the other hand...you can take an ol blacktop L head and park it in a field, wait 15 years, drag it out of the weeds, hook a battery to it and dump a few cups of gas in it, and chances are itll fire.
That never works on a kohler, onan, or anything else ive found.
Now, when it comes to lasting through abuse, neglect, or just general stupidity you cant beat a tecumseh.
So, IMO...
Kohler-Good for something youre likely to use regularly and take care of (a expensive rider, etc)
Briggs- Good for things you will probably dont really care that much about, that will end up abandoned out back untill 20 years later when you need it again.
Tecumseh- Good for things you just use like a hammer...as in...beat the shit out of, and toss it away till next time its needed.