@Gee
I would rank their albums probably something like this (best to worst)
Powerslave
Somewhere in Time
Seventh Son of a Seventh Son
The Number of the Beast
Piece of Mind
Killers
Iron Maiden
The X-Factor
A Matter of Life and Death
Dance of Death
Brave New World
Fear of the Dark
The Final Frontier
The Book of Souls
Senjutsu
No Prayer For the Dying
Virtual XI
I would say I really do like most of these and it's only once you get into the bottom 4-5 where I go "these are good but they're not AS good". For example even Virtual XI which is my least favorite has The Clansman which would be among my favorite songs by the band. It's hard to rank their albums though because I look at albums in the middle (like Dance of Death or Brave New World) and I think "they're still very good"
Nice run of shows you have! Been a while since I saw Alcest but they were great. I'm also seeing Lacuna Coil this fall (not with Machine Head or In Flames though). And I'm actually listening to Enslaved as I'm typing this haha!