See, my question here would be "Why is combat boring in your games?" Because I see a lot of people try to fix D&D by focusing on making the most interesting board game possible, but roleplaying games aren't board games, they're stories.

For me, combat in systems like Shadowrun, D&D, WFRP, Storyteller and so on is boring because it brings the game to a crashing halt. The fact that it can takes hours of table time to play out a few rounds of combat in most of those systems is, to my mind, a far bigger issue than their relative quality as tactical gameplay experiences. Shadowrun tried to layer on more and more special moves and manuevers and combat abilities in the name of making combat more "interesting" and the effect was the exact opposite as so much more of the game became looking up the mechanics for the specific action you're trying to take.

Combat should be fast and vibrant, and sometimes really scary. A firefight in Shadowrun - my go-to because it's the game I run the most - should feel like a shootout from Heat or Ronin, or a John Wick movie. And it's impossible to make anything feel like that when it takes an hour for everyone to get a single turn in.

This is just my take at the end of the day, but I don't think the solution to boring combat is more or better rules. I tried that for years and nothing ever worked. What did work was finally shifting to more narrative focused systems with minimal, versatile rules that allowed me to treat combat just like anything else in the game. That way I could stop focusing on tracking hit-points and initiative, and I can make combat flow into the rest of the rest of the story in a way that feels natural, fluid, and visceral.

I've switched to GURPS because the mechanics aren't so combat-focused, but it has interesting combat mechanics too. A lot of people think it's too complicated, but I've always started off super simple and slow-dripped additional mechanics as players get comfortable with the system and start actively looking for more crunch.

I do think it balances the super involved, tactical combat well by making rounds much shorter. Instead of 6 second rounds with Action, Reaction, Bonus Action, Movement, you have 1 second rounds that give you a single Action. There are ways to squeeze in a bit more on your turn, but it comes with trade-offs, like sacrificing active defense.

Active defense is also a great mechanic. Instead of just swinging at an AC, the defender actually gets an opportunity to Parry, Block, or Dodge. This means a lot less damage gets done every round, but that's balanced by having way fewer Hit Points. I always thought people chipping away at each other's mountains of HP until one dies to be kinda boring and unrealistic. In real fights, it's generally a back and forth of attack and defense until an attack finally gets through and does significant damage.

And I won't really get into all the details of the many different maneuvers available to you, or the techniques you can train. I'll just say that it's extremely tactical and provides for suspenseful combat with real stakes.

I think my biggest complaint might actually be that no matter what you plan to do, you're pretty much always better off just bonking your opponent and doing damage.

Taking an extra turn to sneak around enemies and take them out stealthily? Hitting two turns in a row is better! Grapling an enemy to give your teammate a better chance at succeeding his attack? Still, two bonks will do twice as much damage. Healing? Complete waste of time as long as your HP stays above zero (and even then it only matters when you're still down by the start of your next turn).

But I think my biggest paint points are not even combat related. It's stuff like dark vision, spider climb, passive perception or Alarm, fly or breathless nature. A lot of characters start with these get out of jail free cards from level 1. 5e players will never experience the sense of dread and excitement that comes from exploring a deep windy dungeon with only a couple of torches that may run out at any given moment. 5e players will never struggle to hunt down enough prey in the arctic wilderness because someone will just cast goodberry.

DnD takes everything that makes the journey just as interesting as the goal and throws it away. There's only this fight and then a long/short rest followed by the next fight. That's really all the fun DnD allows its players to have.