In my experience the functionality and reliability of garmin has been almost faultless. Choose to fit your requirements and budget. Couldn’t recommend lezyne. I had two that were returned under warranty straight out of the box because they simply didn’t work. One wouldn’t even turn on.
Second Lezyne. My Macro has been great, Battery lasts for 24 plus hours and charges quickly. It will do nav if you’re desperate, breadcrumb trail style but it’s basically a gps enabled cycle computer and is brill for that.
I’d go for a Wahoo ELEMNT; it does have mapping which I know you don’t want but is useful to have. I’ve been realaly pleased with mine: simple to set up; easy to sync with my sensors; customisable screens; simple to use and reliable.