I think, as LouisWu said, 9s feel eay to play in the store. It's a trap a lot of beginners fall into, I did myself. For years I used 9s and wondered why my vibrato sounded great but I had zero tone. It didn't take me long to adjust my bending technique either. And I have quite a heavy touch on the strings as well, so I buzz a lot less with heavier strings.

I would always take a new guitar (by which I mean either a brand new guitar or a newly purchased guitar) for a pro setup with my favoured brand and gauge of strings. I'm happy to tweak action and intonation and all the other stuff when I change strings, but I like to know that I'm only making minor adjustments to a guitar that's already well setup.