I don’t actively run my tumblr blog anymore due wrist problems, but I thought I’d go ahead and respond since I caught the message notification and have a more simplified personal list to work from. It took me a while to find the post you referenced, but I wanted to start from that. I edited what I had and then added to it.
All are Reid-centric or have at least some particular emphasis on Reid at some point unless otherwise noted.
Personal faves (sometimes only for the Reid parts as opposed to the crime parts) and/or strongly Reid-centric eps are in bold.
Eps directed by MGG are in italics. If there’s nothing else noted about the episode, then it has only been listed for this reason.
I’m also noting a few ongoing storylines when there’s a reference to one of them, though references may sometimes only be small or implied. I’m sure there are a few references I’ve missed or that are in episodes that have little to do with Reid as well. If it states (reference only), then the ep does not contain a significant amount of Reid and is only being noted for the reference.
Past - Reid’s childhood and/or family stuff
Hankel - Reid’s kidnapping/torture and drug use/fallout
Headaches - Obviously, the headaches storyline
Maeve - Maeve arc & aftermath
Moreid - Good eps for Moreid fans like myself, but I’ll only be using this for what I deem as more significant Moreid moments.
1x9 Derailed (Past - implied reference)
1x10 The Popular Kids
1x18 Somebody’s Watching
1x22/2x1 The Fisher King, Part 1 & 2 - Past
2x11 Sex, Birth, Death (Past - implied reference)
2x14 The Big Game (continues with Revelations) - Hankel
2x15 Revelations - Hankel
2x16 Fear and Loathing - Hankel
2x17 Distress - Hankel
2x18 Jones - Hankel
2x19 Ashes and Dust (Hankel - implied reference only)
3x12 3rd Life (relates specifically to Reid’s state of mind in Elephant’s Memory)
3x15 A Higher Power (Hankel - implied reference only)
3x16 Elephant’s Memory - Past - Hankel - Moreid
4x3 Minimal Loss
4x6 The Instincts (continues with Memoriam) - Past - Moreid!
4x7 Memoriam - Past
4x9 52 Pickup (semi-Reidcentric and has some moments any Reid lover wouldn’t want to miss)
4x20 Conflicted - Hankel - Moreid
4x24 Amplification (Hankel - implied reference) MOREID!!!
5x1 Nameless, Faceless (not specifically Reid-centric, especially in the 2nd half of the episode, but contains important event for character)
5x9 100 (not Reid-centric, but I’m listing it anyway because it has a couple of awesome Reid moments)
5x12 The Uncanny Valley
5x16 Mosley Lane
6x2 JJ (not Reid-centric, but you won’t want to miss Reid’s reaction to news near the end)
6x12 Corazon - Headaches
6x16 Coda (Headaches - implied reference)
6x18 Lauren (This episode will make more sense if you’ve at least seen 6x17 Valhalla (Headaches - reference only). It’s not specifically Reid-centric, but has plenty of good, even heart-wrenching, moments from Reid.)
6x19 With Friends Like These - Headaches - Moreid
7x2 Proof - Hankel
7x4 Painless (only because of the prank war with Morgan) Moreid
7x6 Epilogue (Hankel - reference only) Moreid
7x11 True Genius
7x13 Snake Eyes (not Reid-centric, but there are a couple of good Reid moments)
7x19 Heathridge Manor
8x4 God Complex - Maeve - Headaches (very minor reference, basically just a way to write off the headaches storyline)
8x5 The Good Earth (only for the ending with mini-Reid)
8x6 The Apprenticeship - MOREID!
8x10 The Lesson - Maeve
8x12 Zugzwang - Maeve
8x13 Magnum Opus - Maeve
8x17 The Gathering - (not Reid-centric except near end - Maeve)
8x20 Alchemy - Maeve
8x22 #6 (Maeve - reference only)
9x1 The Inspiration (Maeve - implied reference only)
9x6 In the Blood (not Reid-centric, but has some cool Reid moments, Maeve)
9x7 Gatekeeper (not Reid-centric, but has some awesome Reid moments)
9x18 Rabid (only for the scene where he gets to kick a little butt, not the cliched stuff related to working out that reduces Reid to a caricature)
9x20 Blood Relations
9x23 Angels (continues with Demons; important Reid event near end)
10x13 Nelson’s Sparrow (not fully Reid-centric, but significant occurrence for Reid)
10x14 Hero Worship (not yet aired, but should continue to deal with fallout from previous episode)
Well, that’s it so far. Sorry for any errors or omissions I might have made or if I’ve somehow mislabeled something. I was working from memory on a lot of the stuff from season 7 onward and I haven’t rewatched as many of those episodes as I have the ones from the good ‘ole days (i.e. pre-Erica Messer as showrunner).