It's probably been discussed to death already, but Xenoblade 2. Its combat system is legit brilliant, there are so many parts that individually do their own thing, but also interplay and layer on top of each other.
Auto-attacks lead into arts, which lead into specials
But also driver combos and blade combos
Which both combine for fusion combos
Blade combos provide extra damage and effects, seals/debuffs, and orbs
...which lead into chain attacks and full bursts
But fusion combos also flow into chain attacks and result in huge damage with or without orbs
Fusion combos have two different types that do different things
DoT is a whole other things that you can set up with fusion combos, and stacks damage with everything else
There are like 50 different ways to play the game. It's honestly kinda impressive how well fleshed out and cohesive it is, and the next game feels like a step backward with how tacked-on some of the mechanics feel.