Alright I'll do a serious post, and friggin' Cobbler's suggestion of comments is a good one.
Porcupine Tree
1. Piano Lessons
2. Fadeaway
3. Pure Narcotic
The top two have been solid for a long time now. There's a fair bit of competition for the third spot - in particular I could've gone with Waiting Phase One or The Rest Will Flow - but Pure Narcotic has a special place for me at the moment for the "leave me dreaming on a railway track" verse.
Pure Reason Revolution
1. Goshen's Remains
2. Deus Ex Machina
3. Arrival/The Intention Craft
Honourable mentions: The Twyncyn/Trembling Willows, Nimos and Tambos, In Aurelia. I've actually never been able to come up with a PRR ranking that satisfies me, so the numbers are just nominal. Any of the six songs mentioned in any order is fine. No other band has written songs with such impeccable, evocative soundscapes.
Alcest
1. Tir Nan Og
2. Printemps emeraude
3. Away
Another impossibly hard list. The opener and closer of Souvenirs d'un autre monde probably have the top two locked down, because Printemps emeraude is basically the definition of everything blackgaze should be and Tir Nan Og is impossibly beautiful, but choosing a third was brutal. On another day it could've been Percées de lumière, Écailles de lune (part one), or Summer's Glory, but Away has become really significant to me lately. It's a wonderfully calming song, and how can you go wrong with Alcest and Neil Halstead of Slowdive collaborating?
Agalloch
1. She Painted Fire Across the Skyline
2. This Old Cabin
3. In the Shadow of Our Pale Companion
Am I cheating by including She Painted Fire as one song rather than dividing it into three parts? I don't care. You really have to take it as a whole, and it's an atmospheric black metal masterpiece. This Old Cabin is one of their earliest songs, before they'd fully evolved from being just a black metal band into something more, but it's a fucking classic, and In the Shadow is the best product of their evolution into an almost uncategorisable metal band incorporating elements of multiple genres without ever being fully any of them (black metal, doom metal, post-rock, neofolk, etc.).
Crowded House
1. Recurring Dream
2. Anyone Can Tell
3. Kare Kare
I, uh, have a full ranking of all Crowdies songs with comments here (fuck I must've been bored in 2010):
https://rateyourmusic.com/list/Axver/recurring_dream__every_song_by_crowded_house_ranked/
The Chills
1. Effloresce and Deliquesce
2. Pink Frost
3. Part Past Part Fiction
If your top three Chills songs doesn't include Pink Frost, you're probably doing something wrong, and Effloresce and Deliquesce chooses itself for me because it captures everything I love about the band: Martin's eloquent yet effortless lyricism combined with shimmering, jangling guitar notes just spilling out of the speakers. It was hard to leave out songs like Male Monster from the Id, Sleeping Giants, Come Home, February, and Underwater Wasteland.
Pinback
1. Grey Machine
2. CLOAD "Q"
3. Scent
I must be crazy: two of my top three Pinback songs were mere bonus tracks, and I used to hate my number one. I really can't fathom how Scent missed Summer in Abaddon or CLOAD "Q" Information Retrieved; they're absolutely infectious. As for Grey Machine, I used to think it was the only weak thing about the Offcell EP but this great epic has long since wormed its way into my heart. My apologies to Non Photo-Blue, Microtonic Wave, From Nothing to Nowhere, and Tres.
Ride
1. Leave Them All Behind
2. Seagull
3. Vapour Trail
I originally had Chelsea Girl in third because it's such a damn good shoegaze pop track, but omitting Vapour Trail is probably a criminal offence. Seagull is basically exactly what I ask for from shoegaze, and I've said before that I consider Leave Them All Behind to currently be my favourite song of all time.
Ladytron
1. Playgirl
2. Destroy Everything You Touch
3. Discotraxx
This gives a false impression that Velocifero is not my favourite Ladytron album; the next few songs I'd list comprise mainly material from Velocifero. But Playgirl and Discotraxx are incredibly addictive electropop tracks, and Destroy Everything You Touch is the perfect summation of Ladytron's sound, those powerful synths with a dark, punkish undercurrent.
U2
Oh fine...
1. A Sort of Homecoming
2. One Tree Hill
3. Heartland
I've probably said more than enough about these songs throughout my billion years on this forum. Suffice it to say that I think these are the three moments where U2 came closest to musical perfection.