For me, combat of a game as a whole includes both the combat system as well as the enemy design, so
Sekiro- The best take on a back-and-forth type of exchange, whereas almost all other games are more your turn/my turn style of approach. Very amazing for a first attempt, especially with the enemy/boss designs, but still plenty of room for improvement. I'm hoping they manage to make a leap much like they did from DS1 to DS3.
MHW- Not really this gen specifically, but MH easily has the best large monster/enemy moveset designs of any game. Just want to include them somewhere. Weapon moveset design is also extremely varied and unique. Extremely high skill ceiling (part targeting is super hard to master and do consistently, especially with such a large variation of monsters) allows for a crazy amount of room for personal improvement. Extreme behemoth is a triumph.
Tales of Berseria- Best character swap system I've ever played with. Very good resource design in soul gauge in relation to character skills and swapping. A ton of abstract mechanics that only becomes useful in the hardest difficulty, but works very well together at that difficulty level. Individual enemies are fairly basic with small moveset but good variation across the board that allows for varied types of encounters and largest fights in an any RPG that I've played. Boss design is very bad unfortunately, and cannot hide behind quantity as normal encounters can.
GoW- One of the best 1vX games I've ever played. For having an over-the-shoulder cam, the controls were super smooth for dealing with large packs of enemies. Enemy design has sufficient amount of variation as well, making a lot of fights very dynamic as you need to change approach depending on which enemy is coming at you. Skills could be polished a bit more. Bosses are bad, and story bosses are more for spectacle only. Secret boss is also subpar due to the design of having you fight each mechanic separately then combining them. If it all just came at once it would have been a better experience in my opinion.
FF7R- Best hybrid that has more rpg elements being central to the combat system. ATB as it is designed is a perfect basis to expand from, and a lot of bells and whistles can still be added. A strong focus on quality over quantity for abilities and mechanics produced 4 very unique characters with little overlap and few useless skills. Regular enemies could have more interesting movesets (buffs and debuffs being made more prominent in a FF game would be nice). Camera improvements can be made so that in the future it would be possible to fight even larger groups of enemies. Large enemy type boss fights are extremely well done, almost like MH lite in design. Humanoid type bosses could use improvements.
Honorable mention goes to DS3- Soulsgames have very basic player side design (not a bad thing as it fits the game very well), and all of it hinges on enemy/boss design. DS3 has the best selection of bosses, both large and regular sized, of any game that I've ever played, but its player side options prevents it from being included.