>>718260325
SL = LR > 3 ≥ N > MoA ≥ AA > 2 ≥ PP = 1 > power gap > FA ≥ 6 > VD ≥ 4 > NB > 5 > FF

ACE2 ≥ ACE3 > ACE1 power gap > UC > ACEP > even bigger power gap > ACER

SL and LR positions are nonnegotiable. They are THE franchise and the best iterations of their era which was the peak era.

PS3 era is arguable to some extent. It's fine to prefer FA over VD or vice versa but 4 is too anemic/shallow/downgrade to be elevated higher despite the good presentation and OST (FA's salvage job took it in a fun drastic direction but also the one that would erase AC if they were to adopt it fully.)
Vanilla 5 is too MP marred, like a GAASlop and doesn't deserve recognition due to its misguided direction it was trying to take. VD was an admirable salvage job all things considered.

NB isn't a bad game mechanically but it's too anemic in content. It was done as a quick stopgap for the PvP tournament scene which was a thing in Asia at the time.
FF is fun for what it is but it's an AC game in franchise name only. Other 3 PSP ports of 3/SL/LR are pretty much same games except with miniscule additions (few new parts, few new arena enemies, some AI adjustments) and are not worth ranking separately.

And finally there's 6. Despite superficial similarities this game deviates from the formula even harder than 4 and 5 did. Its lock-on turns it more into a arcade Gundam Versus game mechanically so it's difficult to slot it in with the rest of the series ranking. It's a good action game, it's a great mecha game, it's not really a faithful Armored Core game.

Thank you for your attention to this matter.