I have two 300w Won Bros Pro heat IC heaters, they've been working flawlessly for aprox 2yrs. I also use Visi-Therm Stealth, had a 150w been working very well for 1yr, only note is that temp settings have fallen off a bit.
I recommend these two brands for good unbreakable/shatterproof heaters.
I hear Azoo come well recommended,