3.5 Briggs should be just as good or better as 3.0. Give more details on the issues of both. Backgrounds of use yearly maintenances, X fuel, oil, filters, Etc.

I have thirty year old no-name hardware store push mower with 3.75 B&S engine. Bought it for twenty bucks two years ago.

And a 6.75 B&S Toro the neighbor gave me. And a Craftsman 6.5 B&S.

I like the old one the best. It is light and fun to push. It only has side discharge. The two newer ones have mulch, side discharge, and rear bagging. And self-propel.

But the oldie is still my favorite. All have enough hp to get the job done.