I keep finding myself drawn towards tactics games on an aesthetic level, and then bouncing off of them because something about the flow of play feels wrong. It'd be fun to make my own game to try to make it click.
Certain kinds of competitve strategy games (namely stuff like MTG or Root) work for me, maybe because the human component adds a layer of unpredictability that I can actually enjoy.
I don't like combat being represented as attrition. Stance-based systems or bust.
In roguelike-style games where you move across a grid one square at a time, "parity" is a critical mechanic that I just really don't like. I'm imagining a situation where you reduce the impact of parity by having a rolled contest to see who gets to start leading the fight, so that moving next to an enemy isn't just always exposing yourself to a free hit.
In tactics games, it can be hard to capture the element of surprise -- the way a single well-placed unit behind enemy lines can wreak massive havoc. I suppose the main way of re-creating this are fog-of-war and bluffing mechanics.
On the note of bluffing -- can bluffing feel good against a computer? What if the AIs had "personalities" that you could play against when bluffing? Of course, with enough datamining or whatever the illusion of bluffing would disappear and it would just feel like random chance again.