1. Final Fantasy 15, because it will run on a much more powerful hardware and has a bigger budget, but it will be emptier, than Xenoblade X's world. Just compare FFXII and Xenoblade...
2. Xenoblade X
3. Xenoblade X: Hold X to do everything in FF15 can be called a battle system?...
4. Xenoblade X: Xenoblade already streamlined everything that was wrong with JRPGs.
5. Can there be a draw? Both will suck IMO. Xenoblade had a promising story at the start, but it went downhill after a certain point and it didn't make any sense by the end... I lean toward Xenoblade, because recent FF stories were bad from the start and Nomura isn't involved any more with FF15. Yeah, i'm that kinda guy who still likes KH's story.
6. Xenoblade X: I put 140 hours into Xenoblade and still didn't killed the penultimate boss.
7. Xenoblade X: Judging by the trailers FF 15's enemies looks uninspired. Haven't we already seen imperial soldiers and behemoths already in like every FF?
8. Xenoblade X: FF15 will probably be more of a story focused game, while Xenoblade already had tons of side quests and it was very streamlined and interesting.
9. Xenoblade X
10. Xenoblade X, I will wait for the definitive edition of FF15 on PC.

Hmm, i may sound a bit biased, but i WAS really hyped for FF15, but the more i hear about the game, the less i like it. I think it was a mistake to give the game to another director and start it over. Nomura's vision was more cohesive and the sudden change to open world design sounds fishy... It's like they went into this direction, because it's cool these days, but i would liked it better, if it would be still a "mature Kingdom Hearts".

Oh yea totally makes sense to compare xenoblade to final fantasy XII to draw conclusions.

As far as sidequests and a living world go you can compare Xenoblade with any FF game.
As I said in my post FF was never really about side quests or a living world. It was a very focused experience with checkpoints. Sometimes there are optional objectives and places to go but these rarely add to the world and are just something like bonus stages.

Not saying that Xenoblade was much better in that regard but it was always brimming with additional characters and quests in every area.

They're just very different games with different goals.

I'm getting both, so my take... It's honestly very difficult to say, because there is still so much unknown about FF XV. I want to wait until they show someone playing the game in a like demo feel. Like what Nintendo did for XCX at E3 with that massive gameplay reveal, which was awesome. Some of my thoughts might not be true simply because we haven't seen enough information on FF XV. Some of the following are guesses based on what I've seen so far... 

1) XCX
2) FF XV
3) ** Too hard to tell right now IMO. FF XV looks nice, but it looks too scripted. If that is what the actual gameplay will be when I'm playing throughout then I want to give the edge to that. 
4) Honestly no idea. Innovation is too subjective to describe espiecially when people have different meanings for it. 
5) Too soon to tell. My guess FF XV
6) XCX. Massive world, and quests, etc. 
7) Both look nice so far, but I'll give the edge to XCX since I've seen more. 
8) XCX
9) XCX. As I feel people's expectations for FF XV will be too high and honestly I don't have that much faith overall in SE as of now. 
10) Both day one. 

1. Will Have The Bigger World? (In Actually Traveling Land Size) - XCX. FF15's is obviously the much more detailed of the two, which make me skeptical as to it being larger. It trumping XCX in both would be quite the accomplishment.

2. Will Have More A Depth Feel to It? (Talking World, as in Landscapes/Citys/etc) - I expect XCX's will be more varied/interactive, but FF15's will feel more "alive".

3. Will Have The Better Combat? - Tie. They both have very different goals.

4. Will Innovate better Gameplay? - Tie. Neither looks like they "innovate" much. Not that i think it really matters. At all.

5. Will Have the Better Story? - Tie. I expect XCX's will be deeper, but FF15's more relatable too.

6. Will Take Up Most of Gamers time? (Replay value+Longevity) - XCX, for the same reason as point 1.

7. Will Have The Better Enemy Designs? (pls note this isnt graphically, we all know FFXV wins [X1/PS4]) - FF15. They've done a great job of fitting both the "fantasy" and "reality" themes into the enemies. XCX's are perhaps more imaginative, but at the same time more expected.

8. Will Have The Best SideQuest? - Tie. XCX will have more, while FF15's will be more unique.

9.  Overall Better Game? - XCX will probably be the "better", but i'm expecting to enjoy FF15 more.

10. Will You Get Day 1? - Neither.

Lol at the attempt to cover the fact that this is just a thread to stir the pot.

Anyway, I'm getting both eventually. Xenoblade on day 1, FF XV together with a PS4 when they're cheaper and have games that appeal to me.

Nobody knows which game is "bigger" and "better". Nobody knows how the plot unfolds, etc. Last thing you might know, Persona 5 or even a new Star Ocean turn out to be better games.

Hmm, wasn't FF12 the first open world mainline Final Fantasy game? Why couldn't be it compared to Xenoblade? It has a lot in common with Xenoblade. Both focused more on world exploration, side quests and hunts, than linear story telling. Both had a similar combat system: move close to do auto attack and take actions manually, when needed. Since neither FF15, nor Xenoblade X is released, i think it's fair to compare a company's past games to draw comparison and Square Enix didn't developed outstanding open world games and Monolith already proved that they know what they are doing. FF12 was good for it's time, but it had too many flaws.

1. Will Have The Bigger World? (In Actually Traveling Land Size) Xenoblade.

2. Will Have More A Depth Feel to It? (Talking World, as in Landscapes/Citys/etc) Xenoblade.

3. Will Have The Better Combat? I'll say Xenoblade for now because we know almost nothing of FF15 battle system.

4. Will Innovate better Gameplay? I don't think any of those two will innovate much, they're basically using what has already been done.

5. Will Have the Better Story? Xenoblade. FF 15 seems to be following the cliché of "protecting the crystals and save the world from evil empire" from previous FF while xenoblade put's you exploring an uncharted planet.

6. Will Take Up Most of Gamers time? (Replay value+Longevity) Xenoblade, if it's even remotely like the first game.

7. Will Have The Better Enemy Designs? (pls note this isnt graphically, we all know FFXV wins [X1/PS4]) Could be a tie, from what we've seen so far.

8. Will Have The Best SideQuest? Xenoblade, if it's like the first game.

9. Overall Better Game? FFXV/XCX......... Both, Who Cares!!! Xenoblade.

10. Will You Get Day 1? (FFXV/XCX/Both!) Probably neither.

1. Xenoblade

2. FFXV

3. FFXV

4. FFXV

5. Xenoblade

6. FFXV

7. FFXV

8. Xenoblade

9. Both!

10. Both

No. I wouldn't call it open world at all.