I have 2 dual port Battery Tenders at home. Both are 10+ years old and have worked flawlessly. I have 5 individual ones at work that I use for rentals and I've had zero issues with those as well. Make sure your connections are clean and tight.
I have a tender on my sled and wheeler batteries and they seem to last just fine. I do not have a good battery charger/starter though. Just a cheap Northern Tool one.
I'll check what we use at work but I'm pretty sure they are battery tender brand. We use them consistently on vehicles that we test. Only time we ever have battery problems is when the vehicle is put out in the parking lot for a long period of time.