Very good question. I am in search for new heaters. I have had 6 heaters go bad in the last year.
All of them were titanium.
2 Azoos that electrocuted my tank and killed 33 banggai babies.
1 Via-Aqua titanium stopped working
2 GenX rebranded titaniums that stopped working
1 GenX rebranded titanium that was DOA and replaced
I just got (2)-500W and (2)-350W Won Bros. titanium heaters, and so far, they are rocking the house. I've had them for a couple of weeks. My luck with heaters long term is crap, but I hope these do better for me. I got separate controllers for two of them (other two on ACIII), which was another $48 per, but so far so good.