The real answer is that NOBODY makes a solid, reliable heater. The only way to be safe is to have redundant control.
Many achieve this by using a heater with it's own thermostat, plugged into a controller that has a slightly wider range. Heater's thermostat gets stuck, controller's thermostat takes over.
In my case, I've got a heater with no built in thermometer, plugged into an Inkbird controller, with _that_ plugged into my Apex. Inkbird runs the heater. If it fails, temp goes out of set range on the Apex, the Apex shuts it off, and I'm alerted. Seems a reasonable solution.
As a cheap, non Apex solution, a decent heater controller, like an Inkbird, plugged into the AutoAqua Smart Temp is probably a solid option. The AutoAqua shuts your heater down if it exceeds 84f. Not great, and not configurable, but hey, it'd help keep you from making fish soup.
As for controller brands... I've been using Inkbird for years. Currently, I've got a BRS rebranded Inkbird, but I wouldn't really recommend it over the other Inkbird offerings.
The Finnex stand alone controller looks like a solid, reasonably priced option.