Okay, so...

Pre-timeskip Luffy developed enough to use Gear 3rd

vs.

Normal Saiyan Goku.

Honestly, that'd be quite a fight. Goku's got more options (flight, energy blasts), but Luffy's impervious to everything else he's got.

Also, I'd argue in a fight that Luffy's smarter.

It must be a fight about food, that's the only possible way