Briggs has been around a long time, they make a decent product and replacement parts can be found just about anywhere.
Kohler and Honda are also very good, not as easy to find parts compared to Briggs, but that should not be a deterrent.
Nowadays, the "Chonda" seems to be saturating the market, and as much as I hate to say; they seem to be doing OK. (I call it Chonda, which in my opinion is a Chinese copy of Honda)
The main thing you should ask is "Where can I get service after I buy" If they don't have their own service department, be prepared for some bad experiences.