I love pretty much any pairing I'm writing. I most often get brain worms for chanlix or chansung but every ship has its pros and cons for me. I do think that I most often gravitate towards Seungyang when I'm writing them even if they're a side couple, I become most interested in them and their dynamic so maybe my answer would be Seungyang. As far as motivation goes, I use writing sprints to get myself to write, but I also motivate myself by really throwing myself into the fic. I don't know if you saw my recent issues with the fic I just posted but I hadn't delved into the character backstories and dynamics and I was really unmotivated as a result. Once I figured out those deeper elements , I was a lot more motivated to finish. I'm also just very motivated by the dopamine of posting a fic. I edit as I go so I almost always post within an hour of finishing a fic.