my babe preferred my left when we were still breast feeding. I just always started with my right. the way I saw it, they're obviously the most hungry at the beginning of the feed, so I felt that she'd care less about the preference at least until she got a little full.
I try to feed my daughter on the one she doesn't like when she's hungry but not screaming mad kind of hungry. I know she typically eats every hour and a half so when it's time to eat I just got ahead and feed her before she fusses about it. so all day long I generally feed her on my left and pump on my right, until bedtime when it's time to cluster feed and I need both sides for that lol.
That's how mine was in the beginning idk why he preferred the right but I just kept at it no matter what if he got mad if put it away then when he cried again to nurse I'd start over again
Mine proffers my right over my left. I feed her on my left more than my right now just to keep my supply even in both sides, but she absolutely refuses my left all night long.