For me Xenoblade Chronicles X did quite a few things better than Xenoblade Chronicles:

1. Exploration was enhanced by the map and probe system.

2. Combat and gear was more complex and interesting.

3. Side quests were great.

4. End-game is a lot of fun.

5. More real-world character themes and philosophy in the story, rather than the abstractness of Xenoblade Chronicle's gnosticism. Not necessarily better, but different. As far as science fiction goes, Xenoblade Chronicles X is just harder scifi than Xenoblade Chronicles.

I just wished the story didn't fade into the background so much, and that they had confirmed any intentions to make a sequel, having known how the story ends. The pacing of story content was a big negative for me. The cut-scenes until the last chapter were pretty bland and too dialogue-based. I also wish there were more centralized settlements and towns to explore. Otherwise I'd say a solid 8.5/10 due to the deep and interesting game-mechanics, exploration, and side-quests.

Xenoblade Chronicles 2, in comparison, improved on many things (particularly story presentation, some combat mechanics, and towns), but also was even less polished as far as Quality of Life and UI are concerned, and regressed in terms of side-quests and endgame content. I'd give Xenoblade 2 a 9/10, mostly for its story, handcrafted villages/locations, and the blade system.

Xenoblade Chronicles was very polished, but was also a less ambitious of a game than Xenoblade Chronicles X and Xenoblade Chronicles 2. I'd give it a 9.5/10, which is probably the best for any Xeno-game (including Xenogears.) It excelled at many things, was good at most things, but I can't say it was bad at anything really, unlike other Xeno games.

If I were to rank all Xeno games, it would be as so:

(Xenoblade Chronicles >= Xenogears )> (Xenosaga: Episode III >= Xenoblade Chronicles 2) > Xenoblade Chronicles X > Xenosaga Episode I > Xenosaga Episode II.

Xenoblade Chronicles gets a 9.5, while Xenosaga Episode II gets a 6.5.

5. Hmm, I don't know. The ending of XC1 (SPOILER) revealing it is all just a simulation and the "god" is just a crazy scientist was one of the wackiest syfy things ever lol.

I stopped reading at XC2 cause I don't want any spoilers on that game lol

I've heard people doing the side stuff in this game can easily spend 300+ hours, which is just insane to me. I also am still curious how it all ties together. I've read quite a few theories about this topic, even ones suggesting it shares the same universe as xenogears and the other series. 

Would write a whole essay on XCX, as it introduces a lot of mixed feelings for me after coming fresh off the heels of XC, a game which i consider one of my favourites, but i'd like to only say that you hit the nail on the head so hard on XCX being 'Too much'. I feel that putting other issues aside it is it's biggest flaw. To make things worse, i feel this issue is most magnified in management, resulting in a game where you have to put a disgusting amount of time into menus and sorting things out.

I'd probably disagree with you on the story though. The premise is a very promising one, but the way it's structured with side quests, fairly dull characters in my opinion and a lot of uninteresting side-plot, again in my opinion, makes it quite weak, especially compared to the first. Having a severe lack of real plot-twists (Or i guess one that for me is a little late) only makes it worse.

I don't want to go into spoilers, but just take note of the Architect's real name and that cutscene at the beginning of Chapter 9, then compare that info to Xenoblade 1 and it should all click.