Who is stronger goko or ben 10?

stronger

First of all, it's Goku. Second of all, taking your question literally, Ben Tenison is a scrawny little teenage boy, he's quite weak, where as Goku is a super strong alien who can punch through an entire mountain, so in the most literal sense, Goku is stronger (has more physical strength) than Ben 10.

As for opinion, well even including Ben 10's alien forms, I think Goku would still win in a battle, but there's no exact answer to this, that's just my personal opinion.