I'm more picky about buckles than width. Jackson's also a 'bigger' small dog - not teeny tiny. Like I love CollarMania's plastic snap buckles. I do 3/4" collars on him from there, but he could likely pull off a 1" tag collar. But their buckles are somewhat curved and not just... straight if that makes sense so they never look too big on his neck.
With leather, I always taper to 1/2". I wasn't a fan of Ella's Lead collars on him because thick d-rings, thicker leather and wider-ish buckles IMO. I love Paco and Karma's collars on him the best for sure.
1" tapered to 1/2" karma:
3/4" tapered to 1/2" paco:
3/4" all around collarmania:
He's like 18lbs, 19" girth, 12" neck.
I am a huge fan of harnesses too though. I can't imagine walking him on a collar now, tbh. He always walks so awkward on one anyway, I always feel like I am choking him- he doesn't really ever pull, but I still do. Also super easy to 'helicopter' him up into my arms when necessary. I like difference harnesses for different reasons though, but I'm also just obsessed with buying dog gear
I usually end up using the Puppia harness for every day general usage.