Gone a slightly different route with my rankings, going through the albums and selecting tracks that, if they came onto my random playlist, I would listen to almost 100% of the time. Any song that I would potentially skip isn't included. Doesn't mean those songs aren't good or even great, just that I'm not compelled to listen to them every time they come on.
Lunar Strain - 1 (Upon an Oaken Throne)
Subterranean - 1 (Stand Ablaze)
The Jester Race - 6 (Moonshield, Artifacts, Lord Hypnos, Dead Eternity, The Jester Race, December Flower)
Whoracle - 5 (Jotun, Food for the Gods, Gyroscope, Jester Script Transfigured, Episode 666)
Colony - 5 (Embody the Invisible, Ordinary Story, Colony, Zombie Inc, Insipid 2000)
Clayman - 6 (Only for the Weak, As the Future Repeats Today, Square Nothing, Satellites and Astronauts, Swim, Suburban Me)
Reroute to Remain - 6 (Reroute to Remain, System, Cloud Connected, Minus, Dark Signs, Black & White)
Soundtrack to Your Escape - 4 (The Quiet Place, Touch of Red, Like You Better Dead, Evil in a Closet)
Come Clarity - 4 (Dead End, Vacuum, Crawl Through Knives, Vanishing Light)
A Sense of Purpose/Mirror's Truth EP - 3 (Condemned, Eraser, Abnegation)
Sounds of a Playground Fading - 6 (Sounds of a Playground Fading, The Puzzle, Fear is the Weakness, Where the Dead Ships Dwell, Ropes, Liberation)
Siren Charms - 1 (With Eyes Wide Open)
Battles - 0
I, the Mask - 3 (I, the Mask, Deep Inside, Stay With Me)
Unsurprisingly, the only album to register a 0 was Battles. Closest to being in the list would be The End or Wallflower, but both still rank somewhere in the 7 to 7.5 out of 10 range for me, so not unskippable. Siren Charms comes close, but I really like WEWO. Very classic IF style ballad which just sneaks in there. For the record I didn't include covers, but if I did then Clayman would be at an 8 as I would include Strong & Smart and World of Promises.
Generally speaking the pattern reflects how I've been feeling about IF throughout the years. Starting off strong with many songs I love, then declining slightly around the mid-period, a brief spike at SOAPF and then total descent into the depths. I might have been a bit generous with ITM, but I do really like all three of those tracks. Honestly I think Foregone might be another zero though. Not in that the songs are bad, but I haven't had the inclination to re-listen to any of the newly released singles so far... so that doesn't bode well.