For me it has to be Clancy. Before Clancy came out, Vessel was my favorite and I thought nothing would change that but I was WRONG. I think it's my favorite, not only because it's an incredible album, but because it came into my life at the exact moment i needed it. A perfect example would be Next Semester, that song SAVED ME, it felt like the song was describing what I was going through at that moment. I told Tyler how I felt and then he wrote Next Semester. Oldies Station and ATROFD changed me completely too. Also the fact that I heard several songs from Clancy live made me love them even more!! And not to mention the lore that came with that album. I just feel it's an album I can relate to a lot. Bonus points for the proctologist lyric in Lavish LOL.
btw, thanks for appreciating SAI, I really love that album too, it's the first one I listened when I became a fan!