We've tried a lot of different harnesses. We use different ones for different reasons. I still haven't really found the 'perfect' harness that works for EVERY situation. I'll write up a few reviews, so I can copy/paste this in the future, lol. There's always harness threads that pop up.
Puppia mesh harnesses are our go-to. Every time I try to find something better, or different, we still tend to use them the most. They're super easy to put on, their comfortable for him, and they're cute and come in many different colors. My only complaint is it sometimes seems like it may be too hot for summer (but honestly, he's worn them every summer, and it's never seemed to have been an issue) and they're not good for the beach (sand tends to get stuck to them). They're easy to wash though. And the neck is not adjustable on the regular ones, but the medium fits Jackson pretty well. I was considering trying the Sure Fit version of the Puppia though, because it has slipped over his head once before when I pulled it at a weird angle.
ComfortFlex. I like that it's super easy to put on. The material is comfy and easy for him to move in. I don't like that the width is so big, even for the smaller sizes, and the d-ring is HUGE and like, dangles on his back. So when he runs... it hits him on his back, lol. We used it sometimes for agility though, and we've used it at the beach too.
EzyDog Quick Fit. Again, super quick to put on. It seems comfortable for him. I like the neoprene material on it -- good for water activities. It sits up a bit too high on the chest for my liking (still causing some choking when pulled) and I don't like the placement of the buckle (I always have to be careful not to pinch him). I can't get a great fit on it.
ChokeFree Leather Harness. I don't use this one very much anymore, but I do really like it. It looks classy, it fits him good, and it's somewhat easy to adjust. It is velcro, but it's impossible to to get out of, because of the way the d-ring has to go through the hole when the leash is on. It's fairly thin leather, which I like.