Surprisingly, I find the Apple Watch significantly more comfortable and less perceptible than any other watch I've worn in the past. My theory is it's the contoured back for the heart rate monitor, etc. But maybe I'm just weird.

I think it depends what kind of smartwatch you choose. It should fit your wrist. The amount of people I've seen with e.g. a Galaxy Ultra watch that stands over their wrist on both sides is staggering to me.

For me, the Galaxy Watch 7 in 44mm fits perfectly

They’re not that much bigger than an automatic, though they are heavier than most.

Yeah, they get bigger if you spend more money on them.

I have a Garmin Forerunner 165, it is not very big, and not heavy compared to an old style watch made from metal.