Qt vs non qt. Those pop up from time and some individuals goes absolutely mad and hysterical over it.
As far as the rest of the topics go, not much to debate.
Pick lights thaf fit in budget of what your spending limit is and what you want to grow.
Water quality? Theres the ideal of whats safe and not many debate that.
Coral tanks. Sps lps mixed... most like mixed, some only sps (not many) its nice having mixed since a lot of tanks grow mid to top acro, sand bed bittom rock select lps, mushrooms.. some of those torch tanks though...
Apex vs stuff. I dont see much on that.