7" girth here. Everyone is different and there's no universal answer here. I think it really depends on the receiver
My wife loves (!) my girth for vaginal sex, so we have no issues there and we're a good fit. We both enjoy oral sex and it's always been a standard part of our repertoire, but tbh she has a difficult time fitting me in her mouth, so I think over the years I've had almost as much contact with her teeth as with her tongue, lol,

And she's not into anal penetration of any sort (unfortunately), so that's a no-go with us regardless of my size.
Overall, I'm quite happy with my size and wouldn't change anything, but if "best general purpose girth" == "a dick that fits well in every hole", that probably ain't me.