[Coldsaturn]

Ok I'm back after watching all the cards.

First of all:
I 100% understand you wanting to get Colonel. He's...so good and hot. In terms of narrative enjoyment I would 100% understand if you wanted to get him immediately. Consider that the Colonel is relevant if you actually use Caleb in battles, because for the rest his other 5 star card can be pulled from the Galaxy explorer (which is how I got the Colonel in the first place), so take your time thinking about it. Crates don't expire.

The wedding cards:

- Sylus' card is possibly the best one IMO. There's angst, there's fluff, it adds background lore to his character in the present, it ties back to his myth, it adds a bit of relationship development between them. There's one detail about him that is discovered in Death&Rebirth; nothing you would necessarily consider a spoiler, it was a surprise for us when we read it in the main chapter, it might be a surprise for you to read it in this card -- the final result is the same.
I won't pull for him because I've already spent enough diamonds to get Raf and I want to save whatever I can for the beach banner, but if you know you can get Sy with your precise wish activated (which I remind you works once you don't get the chosen LI the first time around, so if you start from 70 pulls for a 5 star it will activate at the 140th pull) go for it. It's really a gorgeous card.
To get him with 3000 pulls it would mean you are 20 pulls away from a guaranteed Sy's wedding card.

- Zayne's MC has gorgeous hair and dress. 10/10. The story has nice ties to his Foreseer myth, and some fans are even saying that Zayne might remember that life. I don't think that's the case necessarily, it might just be the writers going /wink wink/ at us. The rest is your standard tooth-rotting married-couple fluff only ZayneMC are capable of bringing out. Very nice, but not vital for lore.

- Xavier's is basically the same. Very sweet, a randomly angsty throwback to his anecdote where he first met MC, and that's pretty much it. Very nice and cute and dreamy, nothing new in terms of lore or development.

- Raf's is the outlier here because it's pretty much the only card that takes place in the past, before his branch story. I've rewatched it, read some theories around, but I really believe that's the case. Many fans were left disappointed because after his myth and his spring card and banquet ablaze, they were expecting something of similar weight, instead they got a RafMC that looked like they had regressed in their relationship. I truly think this card takes place at the early stages of their romantic commitment, and there are several dialogue lines that confirm it for me.
Also, there's a bit of background lore for Lemuria, a nice semi-spicy moment, and the average chaos RafMC always cause whenever they're together.
It abruptly ends right after the kindled moment, which left many fans surprised because none of the other LIs do that. But the length checks out, so it might have been a matter of not having enough time to write an epilogue. My headcanon is that they went straight to sex and we are not privy to that.

- Caleb's is the one that is still confusing me the most because while I can rationalize Raf's writing and still place it in the timeline, I still can't do that with Caleb's card. It either takes place before or after his bday, and in both cases we create a weird contradiction for the timing of the start of their relationship. Beside this single point, it's also a very nice card, it explicitly mentions Lucid Dream, adds a bit of characterization to Caleb, it's romantic and angsty, the english localization once again could not avoid the "I don't want us to be siblings" topic. Again very good.

If I were to rate them, as a non-Raf main, I'd say:
Sylus, Caleb, and then Raf-Zayne-Xav (you choose based on your specific preferred vibe)