Awesome points from both maxal and Seloun. I'm gonna throw my weight behind Shallan-Adolin even though my heart originally desired Shallan-Kaladin, and here's why:
I think it just makes more sense for Adolin and Shallan to get together. What does Kaladin bring to the table? He's a Windrunner, yes, but ultimately his arc seems to be pointing towards a "reluctant hero lighteyes." The argument could be made that a relationship with a lighteyes could help him transition into his new status more easily, but with Kaladin heading home I'd wager that he will grow into that as he deals with the fallout of whatever awaits him at home.
Kal has followed the Hero's Journey pretty well so far. It's worth noting that the Hero descends into the underworld where he faces the evil version of himself. This basically matches Kaladin's showdown with Szeth, the pseudo-Windrunner, to a t. (Funnily enough, the confrontation happens in the sky, which would be a clever reversal on Brandon's part). Essentially, he has completed this arc of character development, and now we wait to see what the consequences are.
When I first read the interplay between Kal and Shallan, I wanted it to happen. But as the story progressed I came to realize that Adolin... I'm having a hard time putting this into words, but essentially a relationship with Adolin seems like it has more potential to advance the story. As has been pointed out, Adolin's character arc finally got some progression with the potential of marrying Shallan.
Adolin is still in the middle of his arc, and a pretty big wrench has been thrown into it now that his girlfriend from a minor house has suddenly become a Radiant. There's just so much potential for character development here that it makes me practically giddy with excitement.
Now I'm going to go into wild (and I mean wild) speculation, so I'll spoiler it for those who don't want to bother with that: