Both of witch The Witcher 3 does better than Xenoblade X.
Well no it doesn't, especially combat. I don't dislike Witcher 3's combat like most but it amounts to just parrying, rolling, and slashing. There's really nothing to it and you become pretty overpowered midway through the game. Also, quite honestly the character progression/rpg part is rather lame and uninvolved.
Xenoblade on the other hand's combat is constantly challenging and very involved. The Soul voice system focuses on the party being offensive based. Something the first one wanted to be ,but didn't communicate very well thanks to still having a healer with Schala. There's no real healer in X and so setting up your Soul Voices and having your parties abilities in sych actually matters. Not just for healing, but also damage output and buffs. If you set your parties abilities in sych with yours you'll basically be pressing those "QTE" buttons all the time and constantly be on the offense. It's also fun because it actually adds a very involved timing aspect to the battle system, which of course can be very tension filled.
It also expands on XB's MMOish aggro type gameplay. Attacks are more diverse now and it's not simply just stagger them. For my character they were focused on simply just buffing physical attacks regardless of position, though if you chose another class your attacks would be all about positioning just like the 1st one.
And this also applies to the mech combat when you take on even bigger monsters and the scale of the combat grows. Except there its not about classess and more about what you attach to your mech that creates your attacks.
Of course character progression and classes are much more in depth in XB then in the Witcher 3. There's so many ways to make your character. Even choosing your abilities within a class effects the makeup of your character and how it interacts with your party.
Oh and most enmies have body parts which is an important part of battle. Choosing body parts to attack is important in either winning or loosing.
There's a lot to the combat and preparation. Witcher 3 doesn't even come close and people's complains about it being a janky and unresponsive action rpg would never be applied to XB.
And the quests at the end of the day are the same gameplay wise. Go here, investigate something, or talk, or kill. It's just obviously Witcher 3 has far better writing, story telling, and quest design. Witcher 3 is a fantastic game. The world is detailed and probably feels more alive then anything else.....but XBX is no slouch and easily one of the best(if not 2nd best) JRPG of this current gen.