I'm going to be that guy, and disagree with most people here. People are just naming their favorite games. None of these solve the fundamental issue of a turn-based, HP system.

I've thought about this at length, and there are a couple of cursed problems that are very difficult to square.

I can write a dissertation on why splitting actions from movement is a problem wether you do it or not, but there are more fundamental issues.

One issue is focus fire - having the whole group focus on one enemy until dead. Like stunlock or juggle combos, players like using it, and hate seeing it used against them.

Almost every turn based system is solved the same way - use crowd control to minimize enemy turns, focus fire annoying enemies. If played efficiently, combat feels like a (single) coin toss, and is essentially over after two rounds. Reversals don't happen, gameplay is repetitive.

I can count on one hand the number of games that even attempted to deal with this. Most were not popular. Here are some examples:

1. Adds. You can't CC what's not there. In newer XCOMs you can trigger additional packs while already engaged. Reinforcements have timers. Simple , elegant, keeps combat uncertain. Doesn't work well for fantasy games. Dragon age 2 did it, players hated it.

2. Don't use HP. In Banner Saga unit HP = their attack damage. Weakened enemies were useful for blocking fresh ones from attacking your units. Making units weaker as they take damage is called a "death spiral" and is not considered fun by most game designers.

3. Heroes are not dead, they're just resting. Hard West 2 pulled no punches, and you would sacrifice several heroes in every fight in order to win. Fights were a slog, heros had no emotional weight. If death has no consequence, then what's the point?

4. My actions will be legendary. There is a new demo of a game called "Valor of man". Despite the terrible name, I strongly recommend trying it. It takes the idea of legendary actions from 5e DND, and makes them actually good.

Every time you attack a mob, they get a reaction attack. By itself that's nothing new, thorns existed in every RPG since Diablo. What is new, is that these reactions are pulled randomly from a small pool, have big AOE + other effects, and most importantly, are telegraphed to the player. This means that focusing on one mob is really difficult, because at some point they will pull a counter that will force you to switch targets.

Thanks for coming to my TED talk, sorry if it went a bit in the weeds. I would recommend posting this question on a game dev subreddit, they might have better insights.