Seems like a few simple but good options for 5E combat. One caveat is that if you intitute parrying as optionally free, then everyone will use it, and then it is a longer combat, where D&D as written is assuming you are looking for that one opening, the rolling to hit is not to hit, but to get past their parry and meaneuvers to actually strike.
I liked the Arcane Dueling rules in here, I have used a system like it since 2d edition. The text was clean, and well laid out with one exception, you start to talk about firefights, and then empty space and then rules for oaired initiative, firefights and squads. It was a little confusing.