They have been incredibly consistent given their output is 16 full length albums over 30 years.

RIITIIR, AOE and Below the Lights for me... but I agree with Vellichor .. pretty much every record has its good sides

Go chronologically, they are pretty consistently putting out quality stuff and every album of theirs has something worth listening to

Realizing now the album I have is actually their Yggdrasill demo. I got the vinyl repress for like $10 a few years back. Maybe I'll go chronologically, but they have a lot of releases.

BW - Their debut for me followed by their EP Hordanes Land. Their later progressive stuff has never really clicked with me.

AEO for me as well. shocking to realize later this year it turns 15.

"Below the Lights" is my all-time favorite. It's the one I discovered them with, and it still blows my mind to this day.