You mean like, who the first party member you replaced in combat once you could?

if so then it was Mona and then Ann, because Yusuke and Makoto work better with how I played the game

I dropped Skull. When I got Fox, I immediate migrated to the katana he had, plus the Ice spells were fun. My primary line up with Joker, Panther, Fox, and Queen. After awhile, I realized the pros and cons to each person, so my final lineup consisted of: Joker, Panther, Skull, Noir/Mona. Joker was split into uber damage, and support healer Panther is the hardest hitting Mage, Skull is the hardest hitting Physical Noire's Heat Raiser for boss fights and Mona is the best Healer for standard mob trash grind. I wanted to use Fox and Queen more, but they do not do well end game, as they don't actually specialize in damage like the rest can, so the last of passive buffs really do hurt them in the long run. I min-maxed my party quite a bit and was focused on taking down the optional fight to get the Omni orb.

For my first playthrough, I ran with the kamoshida arc gang for pretty much all of the game, and like my romance choice, I regretted it immensely. Second playthough, I kicked out Panther first chance I had, but not for Fox, since I always decide to solo the rest of that palace. After that the slot kinda rotated. Looked a little like Joker Skull Mona Panther > Queen > Noir before you ask, yes, in both playthroughs i immediately yeeted crow out of my party because he isn't a good party member

For me, I always rotated them in and out, because I knew I'd need them again, so I would usually try to keep them in during grinding sessions in Mementos to keep them all leveled up. As for who I booted out first though; Panther.

I almost always had Yusuke on hand until certain boss battles and same with Mona because he's a great healer, but I wouldn't hesitate to replace Ryuji in a heartbeat

First was Skull for Fox. Then Mona for Queen. I kept Panther in for my first run through the game cause I always do with the early game healers. In my second run, I abused the fact your party could easily get 100% EXp no matter if they were in your party or on the bench, so I was just contasntly cycling though to suit the situation.

For me usually I don't remember if I took out Mona or fox first. But in that moment I did have experience as player from persona, now I would say... Fox, or depending most of the enemies where I will found in the current palaces.