Safest heater for betta tank?

[Epiphanaea]

I have a 5g currently cycling, I plan on getting a betta.  The tank is on my bathroom countertop, and I keep the bathroom door continuously closed because I have plants that need high humidity and cats that like to eat plants. So in the summer it’s pretty hot in there, will probably not need a heater at all - but come fall it cools down rapidly, so I want to be prepared.  
 

I have read so many horror stories about accidentally cooked fish, and most of the nano tank heaters I’ve seen look really cheap and don’t appear to have failsafes.  This makes me nervous.

So, any recommendations?

[xXInkedPhoenixX]

I have really good luck myself with the paddle type heaters (I think they call them flat heaters and the brand I use is Aqueon typically- I use the smallest one). There is no glass to break and their operation is simple. I've had them fail EVENTUALLY, meaning they stop working (the one I had fail is when my Mum drained the tank and exposed the paddle to air which the packaging expressly tells you NOT to do). They are typically preset to 78. If your tank has a lid I have one that is in my 10 gallon tank with a lid and though the heater is preset to 78, the tank is always at 80-82. It is also in a warmer room. 

They're also very easy to hide. 

Edited June 25 by xXInkedPhoenixX