I run 2 smaller heaters, plus 1 large one that is also on a controller.
I use ViaAqua titanium. No issues, and some have been going 5+ years.
I chose them because the electronics for the controls are well away from
the heat of the heater, instead of integrated all into the same tube.
Electronics break down much faster when hot.
I avoid glass ones because of user error. (I dropped on once)