Let's see what I think of the levels.. one-by-one.
Battle levels :
1. Carrotus Squash : definitely a classic. Unmissable.
2. Green Beret : Good old level that I haven't played alot.
3. What is this ?! : Good new level, also unmissable.
4. Rainy Rain Forest : probably a good level, haven't played this yet.
5. Burning Desert : Old level by Blade? Probably one of the levels out of his pack.
6. Higher Fragging Rate : Good level. No problem.
7. Shine-o-rific Land : Good old level, no problem.
8. EvilMike's Hidden Temple : Played this in JB version, and I have no problem with it.
9. Bobo Meats Royalty : This is probably a joke.
10. Battle in the Castle : A level that was in AB6 as well, but I find it a good level.
11 // MyStIc FoReSt CaVe : Another old level that's a bit confusing.
12 // The Dark Fortress : Good level, but it was in AB5 as well.
13 // Plastic Fortress : Dunno alot about this level.
14 // Forsaken : Great level, has to be in.
15 // Toxic Waste : I don't know alot about this level.
16 // EvilMike's Evil Fortress : Great level, has to be in for sure.
17 // Miniature Battle1 : Too small.
18 // Villian Village : Unknown level for me, haven't seen this alot.
19 // Where Warrior Falls : Another old level that's a bit unknown.
20 // Cold Mini Battle : ?
CTF levels :
01 // Bloodbunny's Lair : Very old level and very overplayed. Was in AB3 and 5 as well.
02 // Happy Canyon CTF : Old level, but I understand why it's in and I have no problem with it.
03 // GEMneric CTF : Quite unknown level for me. But I have played this sometimes.
04 // Medieval Skyscrappers : One of my favourite levels.
05 // Sanctuary : Unmissable level.
06 // Slab RatZ : Good level, but could be a bit too small.
07 // One Silvery Penny : Fun level.
08 // Quasar Quandary : Only XLM level in the list, but a good choice.
09 // Surfs Up CTF : Nice level, it's one of the underplayed old levels.
10 // Clipboard Chaos : I understand why this is in. And I have no problem with it.
11 // Sacrifice : Good level that almost won the JJ2WC contest.
12 // Ext Morse : Is this that Space Warbase level? That's quite small.
13 // Apocalyptic Afterworld : Nice level that has to be in.
14 // 7th Lava Fall : Way too big level in my opinion, and a bit confusing.
15 // Anarchy Inn : This deserves to be in.
16 // Glowing Poison : Bit weird layout, but original level.
17 // Happy Castle : Too many dead ends, and it was in AB3 and 5.
18 // Fiersome Flaggin' : Haven't played this alot lately.
19 // Fright Night CTF : Big level, but it's good enough.
20 // Diamondus Warzone : Some people hate it, some people love it. It's very old and overplayed.

Conclusion : A list with old levels and new levels that are mostly by OLC members. No levels out of SuperJazz's pack, or one of my levels in.