my experience with their heaters has not been good. I had one fail immediately, which they replaced under warranty. Then a year or so later I had another one fail....it would flicker on, then off, then on, then off etc. Your mileage may vary.
I have a 100 watt Marineland that is running like a champ after twelve years. It’s the only one I have other than my two Eheim Jagers that keeps the right temperature.
I read many posts about heaters with people wondering about reliability. Heaters are all pretty reliable and there are two main reasons why they fizzle out. Number one is using either too high a wattage or two low. Pick the one that’s just right for your size aquarium as recommended by the manufacturer. If you have your aquarium in a cold room pick the next size up. The manufacturer will advise this in the instructions.
Number two is ignoring the water level indicated on the heater. Even submersibles have a water level indicator line. Unplug the heater when doing water changes.
I agree with @Back in the fold, Marineland heaters are fine. I use them as well as other brands. In my experience, Marineland really stands by their warrantee if needed. Most importantly, size the heater to your tank's desired temperature vs the coldest ambient room temperature.