The easy answer would be Clark/Oliver from Smallville, because well, I came to fandom and started writing fics for them. There weren't many fics out there at the time, and there were some that just used Ollie as a Lex replacement or even as a stepping stone to get back to Clex (something that ended turning me off that ship completely). Other people wrote for them too (and I'm not being humble by saying their fics were better than mine) but I think I was the one creating the most, consistent fanfic about them in those years. So I was really, really into them back in the day, have a whole list of fics that I complied, made a community type thing.
And they'll always have a fond place in my heart, especially since I still write for them.
The most recent answer is Sam/Bucky. I never thought I would love them as much as I did, since I was really into Steve/Tony right after The Avengers movie. I really liked the chemistry Sebastian Stan and Anthony Mackie had in TWS press tour so I liked the potential but once CA:CW hit, that was when I was like "OH, this is totally for me". The frenemies to lovers trope is my favorite, and this ship really worked.
That look in Endgame that Bucky gave Sam totally made me lose my mind in the theater. It was so soft! I thought that was as good as it would get and even though I haven't seen it, TFATWS existing and all the content really made me ridiculously happy. I think they've become my comfort ship for sure.