Most of the races I do here in MN are wetsuit legal, but I’ll skip suits on sprints or hot days.
When I do, I use my Under Armour compression t-shirts - they fit super tight (at the neck too), very few seams, no pockets, dry instantly, and are very comfortable overall. They lack a zipper, but I can’t claim I ever miss that on these shirts, even in hot weather.
But they are not “tri tops”, so I lose style points for that.
Cheers, Chris