Neonchameleon
Legend
Apologies if you felt I was ignoring your point, it was far from deliberate. I have played Basic Ad&D 3.0, 3.5, 4ED, Traveler, Castle and Crusaders and 1 game of some kind of super hero game? Mutants something? As well as a huge variety of home brews of the above systems..
OK. So other than Traveller, literally all those games are part of the D&D family tree. (Including Mutants and Masterminds - a d20 game with the d20 logo and feats - one of the parts of the D&D family tree). And even Traveller is a pretty similar game - the design goal was quite literally "I want to do Dungeons & Dragons in space."
You are preaching System Doesn't Matter when literally all the systems you have played are within touching distance of each other. Of course system barely matters between them - they are all almost the same game and none of them really use the system differently.
This is why I'm suggesting you get experience with very different games like Dread (the resolution mechanic being a Jenga tower), Dogs in the Vineyard (raising dice against each other), or Wushu (the more detailed your description the more d6 you roll and there are almost no other rules).