I've rewatched all 4 with my kids not so long ago.
1st one didn't age as well as I remember it.
Road Warrior was great as ever.
Thunderdome surprised me, I don't remember it being actually quite good, having (IMO) best grey characters narrative of all 4.
Fury Road was even bigger waste of time than the first time I've watched it.
So, for me, Road Warrior, though Thunderdome is, due to greyishness of their characters, close second.