Depends what you mean by best
As a tech I loathe all B & S engines as they are a PIA to work on
If I was to pick a favourite it would be the SV sprint series .
The ones down here fitted with snorkels will just about run forever . require little more than the odd oil change and a pump diaphragm kit every 10 years
The plastic carbs don't corrode , rarely block up and rarely give any problems other than the governor spring going slack