Heaters come and go to be honest, the fact of the matter is, at some point in time a heater/stat is gonna fail no matter which brand you chose, Over the years I've tried them all even back in the days when we had seperate heaters and externaly hung thermostats (silk stats) Visitherm, Jebo, Hagen, Eheim etc, etc,etc,
There is some solace in all of this, I actually did like the Visitherm model as previously mentioned. It seemed to perform the best out of all the ones I'd used previously.
I'm currently trying the RENA Smartheater due to a breakdown in my last one (Eheim Jager)which could have had dire consequences to my tank stocking.
I'm using it in conjunction with an ATC 300 Temp Controller for added piece of mind.
Whatever comes or goes ...make sure you choose a heater which corresponds to the size/volume of your tank
Of-course you could also try a ThermoFilter depending on the size of your tank. (External Canister filter with incoorporated heating element, thermostacially controlled) but quite expensive.
Hope that was of some help to you.
Regards
BigC