This is always tough; my first and last few are always the same, then the rest can change over time. Here goes

1. Season 5 (Swan Song)
2. Season 4 (Lucifer Rising)
3. Season 2 (AHBL2)
4. Season 8 (Sacrifice)
5. Season 3 (No Rest for the Wicked)
6. Season 6 (The Man Who Knew Too Much)
7. Season 1 (Devil's Trap)
8. Season 10 (Brother's Keeper)
9. Season 7 (Survival of the Fittest)
10. Season 9 (Do You Believe in Miracles?)

1. Season 5 (Swan Song) - The Apocalypse has yet to be topped.
2. Season 6 (The Man Who Knew Too Much) - GodCas! and his proclamation unhinged my jaw for roughly five minutes.
3. Season 10 (Brother's Keeper) - The Darkness is awesome, Death was awesome and Dean vs Sam was made of awesome.
4. Season 8 (Sacrifice) - Angelfall. Nuff said.
5. Season 4 (Lucifer Rising) - Ruby dying = Very good. Castiel rebelling was even better.
6. Season 3 (No Rest for the Wicked) - Lilith and Hell made for one... hell... of an episode.
7. Season 9 (Do You Believe in Miracles?) - DemonDean! was a shocker. Plus Dean fighting Metatron was epic, and Gadreel's Heroic Sacrifice.
8. Season 2 (AHBL2) - YED dying, John's return and Dean getting his revenge; all awesome.
9. Season 7 (Survival of the Fittest) - Purgatory and Dick Roman's death, very cool scenes.
10. Season 1 (Devil's Trap) - Weakest of the season finales in my opinion, but not because it is bad or weak, just all the others are better.

First and last two are easy, the rest are subject to change depending on my mood.

1. Season 5 Swan Song. It always has been and always will be my favorite episode.

2.Season 4 Lucifer Rising

3.Season 3 No Rest for the Wicked

4. Season 8 Sacrifice

5. Season 6 The Man Who Knew Too Much

6. Season 2 AHBL2

7. Season 1 Devil's Trap

8. Season 10 Brother's Keeper

9. season 7 Survival of the Fittest

10. Season 9 Do You Believe in Miracles. The only finale that I really disliked.

1. Season 1 (Devil's Trap), Season 2 (AHBL2), Season 3 (No Rest for the Wicked), Season 4 (Lucifer Rising), Season 5 (Swan Song)
2.
3.
4.
5.
6. Season 6 (The Man Who Knew Too Much)
7. Season 8 (Sacrifice)
8. Season 9 (Do You Believe in Miracles?)
9. Season 7 (Survival of the Fittest)
10. Season 10 (Brother's Keeper)


My list is almost in order of appearance. I don't separate the first 5 seasons. Can't do it. Each is flawless, and I can't think of one without the other. Not only is each a perfect crescendo for the season they end and the season they lead into, but also thoroughly rounded episode's in their own right.

#6 goes to Deity Cas. Hated the ill-use of the Campbell clan, and an under-whelming "mother of all evil" Eve, but Cas going all God-like was pretty rad. Not something I would have ever predicted before the season began.

#7 goes to Sacrifice. Crowley's "curing" scene with Sam was above and beyond, and redeemed any and all nonsense elsewhere in the whole season, and "Angels. They're fallin'!" was gold. Holy shit was that line and scene delivered right.

#8 goes to Demon Dean. The episode as a whole was shit, but Crowley's elegy of hope was beautiful ... and not a single soul that watched it didn't say "oh shit" when Dean's eyes opened black.

#9 was the finale of 7. Levi's sucked, and the finale in and of itself was lacklustre. Quite a fitting culmination for such an uninspiring season.

#10 goes to 10. A season so scattered that the penultimate episode should have been the mid-season finale, and the finale felt like it belonged in a random episode three episodes before the mid-season finale - except for 'The Darkness'. The Darkness belongs on the yet-to-be-released Hillywood Lost/SPN Crossover parody.

-Cody

1. All Hell Breaks Loose
2. Swan Song
3. Devil's Trap
4. Lucifer Rising
5. No Rest for the Wicked
6. Sacrifice
7. The Man Who Knew Too Much
8. My Brother's Keeper
9. Survival of the Fittest
10. Do You Believe in Miracles

1: Season 2 All Hell Breaks Loose part 2: First off this finale is unique. Its the only finale AND season to have a
2 parter. I reckon we should be treated to a 2 parter finale once again. It has a great buildup it ties everything
up nicely. Sam is the sole survivor of the psychic children, Azazel is finally killed, John is set free from Hell
etc. So much quality perfectly paced. Beautiful! Oh and they release a mass of demons on the world from a gate of
hell.

p.s I slightly prefer the anime version over the live action one. *ducks under table*

2: Season 4 Lucifer Rising: What could be a more "Oh shit" moment than seeing the devil being released? But lets
step back a bit shall we? Torn between two sides Sam has doubts about what he's about to do. That is until he hears
that soul tearing message from a fake Dean. His path now set he drinks the blood of the innocent woman possessed by
a demon and has the one sided stand off between Lilith and him. The part I loved was Sam becoming so enraged at
Lilith's taunting he digs so deep into the powers of his foul blood his eyes turn black. Wonderful finale overall.

3: Season 1 Devil's trap: *stands up and applauds Nicki's performance as Meg* What an actress. She played badass,
evil and sassy perfectly! She really made that episode many times more enjoyable. I really miss her. As with S2's finale it packed so much in that when I think back I go "wow, how did they fit that in so well into one episode?". Lets not forget this was the episode Azazel was properly introduced which was
exciting!

The classic line that is pure comedy has to go to:

Dean: Where’s our father, Meg?
Meg: You didn’t ask very nice.
Dean: Where’s our father, bitch?
Meg: Jeez. You kiss your mother with that mouth? Oh wait, I forgot, you don’t.

OOOOO BURNED! XD Oh.. I see what I did there..

4: Season 5 Swan Song: The buildup was great, the pacing too and that scene of Sam falling into hell was captivating! Its a real shame the budget let the graveyard scene down. In fact I wish they had far more budget for this episode. I wish they made this season in the anime. It'd be amazing.

5: Season 10 My brothers keeper: I will say this finale didn't flow as smooth as the Kripke ones but its the last 10 or so minutes that make it halfway on my list. Rowena uses the book of the damned and after walks off with both that and the codex. Not good. As a parting gesture she orders Castiel to kill Crowley. Oh no! Then the mark is removed and the Darkness is released and engulfs the Impala with Sam and Dean in it. OH NO! They just released the ORIGINAL evil into the world and they got caught in its embrace. Now unless the Impala can suddenly shut off all air supply and vents etc they've just got a mouthful of that black stuff. Very foreboding for the next season..

p.s Jeremy Carver don't you DARE tell me they get out of that in one piece! As someone said Sam hasn't got his tattoo back right? Hmm? Maybe we'll get our Sam season after all.

6: Season 6 The man who knew too much: I really liked how this ep focused on Sam a lot. The quest in his mind to recover his memories so he can be whole. Again I thought this was well paced (well it was written by Kripke) and didn't bore me.

7: Season 8 Sacrifice: How awesome was it for Crowley to start killing people the boys saved as early as S1? I felt nostalgic at that. Also sad and surprised he killed some (even that women Sam loved). I thought the Sam and Crowley scene was great too and makes this finale stand out more.

8: Season 3 No rest for the wicked: I'm not sure what to say on this. Not much seemed to happen, not much stood out to me. Felt the whole child Lilith scenes didn't seem right for a finale. In fact the only scene that felt like a finale was Dean in hell.

9: Season 7 Survival of the fittest: This season wasn't one of my favourites and the finale wasn't too. There was no zig zag paths to the finish, it was a straight kind of boring run.

10: Season 9 Do you believe in miracles?: I was a little bored.. It dragged on really. Unfortunately I knew what was going to happen at the very scene because I knew before I even began S1 they at some point Dean became a Demon. Whoops. So the impact it left on me was non existent. Lets be honest, unless its VERY well written one of the brothers dying is a bit of a joke. It feels stale.