I've had both and shot both. For me, the 365 wasn't a good fit. I didn't shoot it as well as my 43. I had problems riding the slide release. It was a 50/50 shot if it would lock back on the last round. I traded it for another 43. I liked the trigger better on the Sig and it was smaller, but not enough room to get a good grip.
I carried a Glock 43 for a couple, or three, years but then traded up and switched to the Sig. (Have three of them now.) I like them both but found I’m more naturally more accurate with the P365, even though it was new to me and I’d been shooting the 43 for years. My Wife also preferres the P365. That being said I think they’re both fine guns and I’d trust my life to either.
The G43 fits my hand better and I shoot it better. The 365 grip wants to twist a bit in my hands...it’s the same thickness, but the G43 grip feels a tad bigger front to back. I had problems with my hand inadvertently hitting the P365’s slide release preventing the slide from locking back on an empty mag. I loved the Sig’s sights and the trigger was great.
If I could’ve gotten a better grip on the Sig and could’ve found an aftermarket slide release (raised or fwd “button”), it might’ve well been perfect.
I’d like to try the P365XL but I doubt the longer grip would help much (for me) as my “grip issues” had to do with pistol wanting to twist in my sweaty paws. But it might help. I’ll probably rent one before I purchase another micro.