When looking at heaters, I go with two ideas. One is that most electro-mechanical things do fail and heaters often fail due to the contacts sticking so that the heater stays on. That leaves me to want the smallest heater which is still big enough to get the job done. In ten gallons, that is often too large even at 50 watts. But the fifty is an easy to find, cheap option, so I go with it as a way to increase the amount of time I have to find the problem before the fish are dying.
But on any heater on a tank where I value the fish, I add a second layer of safety. Rather than paying more for a heater, which I have never found that did not fail, I go for using a temperature controller.
With the heater thermostat likely to fail at some point, I want a second line of safety so that the temperature controller will shut off and control power to the heater when it sticks on!
There are many options to meet what you want to do, depending on whether you want to pay a bit less and do some minor DIY work or want a ready made unit for a bit more.
I favor two units which are now listed on E-bay here in the USA. One is the Inkbird 308 for $32 and I find it has everything I could possibly want with alarms and lights, etc, while the other is much cheaper at $12.95 but harder to read the Chinese English instructions and does require adding the wire for power in and out. Perhaps search for "digital temperature controller" for different options?
Perhaps consider how much safer it is with two items to control the overheating? It is certainly nice to trade off not using the small mercury thermometer which is hard to read for the nice large digital that I can read from across the room! When in a hurry, I don't have to go into the room, just stand at the door and scan the temps!