Top 12 mons

Good question, mine would be:
1. Dragonite
2. Rhydon
3. Snorlax
4. Gyarados
5. Vaporeon
6. Blissey
7. Exeggutor
8. Heracross
9. Arcanine
10. Omastar
11. Machamp
12. Flareon

Only managed to evolve one jolteon so far and it had too low IV stats to get into my top 12.

My top 12 (from 3029 to 2257)
Dragonite
Rhydon
Gyarados
Snorlax
Vaporeon
Exeggutor
Flareon
Espeon
Blissey
Donphan
Alakazam
Arcanine

I have candies to power up my Dragonite and Blissey some more but they have been in gyms for a while now so I haven't been able to. The Donphan I caught in the wild at that level but I haven't powered him up as the IV's aren't great. Haven't powered up the Alakazam or Arcanine either as I don't use them much.

Dragonite
Gyarados
Vaporeon
Snorlax
Blissey
Rhydon
Exeggutor
Alakazam
Arcanine
Flareon
Jolteon
Lapras
Pincer
Slowbro
Porygon2
Cloyster

everything else is below 2k.

Dragonite
Blissey
Vaporeon
Snorlax
Espeon
Gyarados
Golem
Rhydon
Exeggutor
Machamp
Arcanine
Jolteon

1. Dragonite (3243)
2. Rhydon (3175)
3. Vaporeon (3045)
4. Snorlax (3013)
5. Blissey (2803)
6. Golem (2800)
7. Exeggutor (2775)
8. Flareon (2764)
9. Alakazam (2663)
10. Jolteon (2632, perfect)
11. Charizard (2590, perfect)
12. Gengar (2525, perfect)

1. Gyarados 2829
2. Snorlax 2792
3. Rhydon 2760
4. Dragonite 2712
5. Vaporeon 2683
6. Golem 2506
7. Exeggutor 2489
8. Arcanine 2355
9. Gengar 2246
10. Jolteon 2204
11. Espeon 2174
12. Ursaring 2125

1. Dragonite (3313)
2. Gyarados (3079)
3. Snorlax (3076)
4. Rhydon (3040)
5. Vaporeon (2972)
6. Blissey (2928)
7. Exeggutor (2718)
8. Alakazam (2660)
9. Arcanine (2643)
10. Donphan (2606)
11. Jolteon (2584)
12. Espeon (2519)

I only have a couple of differences. I have a 2955 Tyranitar and in my 13 spot I have a 2526 Muk.

1. Tyranitar
2. Dragonite
3. Snorlax
4. Gyarados
5. Blissey
6. Rhydon
7. Vaporeon
8. Espeon
9. Exeggutor
10. Golem

Currently my top 12 species:
Vaporeon
Exeggutor
Snorlax
Flareon
Espeon
Pinsir
Jolteon
Poliwrath
Crobat
Kinglet
Vileplume
Alakazam

1. Dragonite 3326
2. Snorlax 3079
3. Gyarados 3070
4. Vaporeon 2941
5. Espeon 2710
6. Rhydon 2618
7. Flareon 2605
8. Arcanine 2602
9. Exeggutor 2583
10. Alakazam 2471
11. Gengar 2413
12. Golem 2411

Dragonite
Blissey
Vaporeon
Snorlax
Espeon
Gyarados
Venusaur
Rhydon
Exeggutor
Machamp
Arcanine
Lapras

Mine seems a lot different. Also waiting for a good dragonite, already got almost 400 candies

1 snorlax
2 blissey
3 vaporeon
4 exeggutor
5 dragonite
6 flareon
7 golem
8 rhydon
9 alakazam
10 jolteon
11 gyarados
12 muk

1. Dragonite 3229
2. Rhydon 3004
3. Gyarados 3001
4. Blissey 2961
5. Snorlax 2811
6. Espeon 2699
7. Vaporeon 2606
8. Exeggutor 2510
9. Machamp 2448
10. Golem 2426
11. Scizor 2411
12. Gengar 2404

1. Dragonite
2. Gyarados
3. Rhydon
4. Vaporeon
5. Blissey
6. Alakazam
7. Snorlax
8. Donphan
9. Exeggutor
10. Golem
11. Machamp
12. Espeon

1) Dragonite 3227
2) Snorlax 3156
3) Gyarados 3082
4) Vaporeon 3022
5) Blissey 2885
6) Exeggutor 2748
7) Rhydon 2708
8) Machamp 2684
9) Arcanine 2651
10) Espeon 2572
11) Lapras 2510
12) Golem 2453
(Flareon 2451, Gengar 2406, Alakazam 2398 just miss the cut)

Dragonite 3508
Tyrannitar 3440
Rhydon 3239
Gyarados 3234
Snorlax 3192
Blissey 3147
Vaporeon 3104
Exeggutor 2863
Arcanine 2787
Charizard 2487
Lapras 2466
Flareon 2406
Muk 2404, Venusaur 2310 and Poliwrath 2301 missed the cut

Vaporeon 1806
Omastar 1621
Tentacruel 1598
Ursaring 1594
Arcanine 1456 (98IV)
Golduck 1308
Poliwrath 1308
Jolteon 1252
Noctowl 1186
Xatu 1155
Seaking 1127
Dewgong 1119

1. Tyranitar
2. Dragonite
3. Snorlax
4. Rhydon
5. Gyarados
6. Blissey
7. Vaporeon
8. Golem
9. Exeggutor
10. Donphan
11. Espeon
12. Machamp

All in order of CP level. Top being the highest obviously.

1. Dragonite (3402 CP, 100%)
2. Snorlax
3. Tyranitar
4. Gyarados
5. Blissey
6. Vaporeon
7. Rhydon
8. Arcanine
9. Exeguttor
10. Donphan
11. Espeon
12. Lapras (2510 CP, 100% maxed)

Tyranitar
Dragonite
Blissey
Rhydon
Vaporeon
Snorlax
Alakazam
Exeggutor
Golem
Machamp
Scizor
Arcanine

...and then
Espeon
Flareon
Omastar
Jolteon
Typhlosion
Ursaring
Lapras

1. Dragonite (3236)
2. Gyarados (2958)
3. Vaporeon (2919)
4. Rhydon (2915)
5. Blissey (2911)
6. Snorlax (2902)
   (The above are also my six strongest Pokes, mostly Vapes, 2 Garys from the water event, and a couple Rhydon between here and #7)
7. Espeon (2682)
8. Exeggutor (2678)
9. Arcanine (2649)
10. Flareon (2600)
11. Alakazam (2531)
12. Machamp (2525)

Followed by Tyranitar (just got him!, 2507), Jolteon (2455), Golem (2392), Lapras (2385), and Scizor (2310).

Going by memory:

1. Tyranitar
2. Dragonite
3. Rhdyon
4. Snorlax
5. Blissey
6. Vaporeon
7. Gyarados
   Large Gap
8. Exeggutor
9. Espeon
10. Golem
11. Flareon
12. Arcanine

CPs are approximate:

Dragonite 3240
Snorlax 3200
Gyarados 3150
Blissey 2940
Rhydon 2850
Vaporeon 2790
Espeon 2560
Exeguttor 2550
Arcanine 2500
Flareon 2450

Above 3000:
Dragonite
Tyranitar
Gyarados
Blissey
Vaporeon
Rhydon
Snorlax
Above 2500
Exeggcute
Machamp
Alakazam
Charizard
Archanine
(also Lapras, Venuasaur, Golem)

1. D'nite (x3)
2. Tyrant (x1)
3. Snorlax (x3)
4. Rhydon (x3)
5. Gyarados (x4)
6. D'nite (x1)
7. Vape (x4)
8. Blissey (x1)
9. Snorlax (x2)
10. Espeon (x1)
11. Exeggutor (x3)
12. Gyarados/Blissey/Donphan

1. Dragonite 3113
2. Gyarados 3070
3. Rhydon 3061
4. Snorlax 2796
5. Vaporeon 2754
6. Espeon 2535
7. Exeggutor 2473
8. Flareon 2464
9. Alakazam 2431
10. Machamp 2414
11. Arcanine 2394
12. Jolteon 2318

1. Gyarados 2855
2. Vaporeon
3. Rhydon
4. Exeggutor
5. Espeon
6. Flareon
7. Jolteon
8. Alakazam
9. Ursaring
10. Snorlax (the only one I've ever gotten)
11. Cloyster
12. Kingler (2076) and I have to go through 34 Eeveelutions before I get there. My collection would be borderline unusable if not for super common Eevees.