I’ll mention my favorite levels too. NOTE: This list is incomplete for three reasons: gimmicks/frenzies/bonus pack levels are not allowed, the levels I am listing I feel are (or would have been) worthy enough for the pack, and that I haven’t beaten the harder levels yet, especially in the PSYCHO, Cunning, Genius, Rough and Fierce levels. I’ll follow a similar format to how Nepster reviewed the levels.
Levels on the 30 that aren’t on my favorite list:
Nice 7 – Together We Sand – this one’s a good level, but I feel that it's slightly similar to Fun 11 with a few more obstacles.
Cheeky 7 – Yours Treely - there's nothing special about the solution, though I do like the visual design.
Dodgy 8 – Synergistic Effect – as Nepster said, the solution is obvious.
Fierce 1 – Dead Is the New Black – I love the trick used here, but it doesn’t feel like it should be in this collection pack. Also, it feels odd that this is the first level of Fierce, despite it being supposedly the easiest Fierce level.
Levels on the 30 that are my favorites:
Mild 12 – On the Pier – a very fun “find a safe way” down level with so many solutions.
Mild 30 – You Just Lost the Game! – a great way to conclude the Mild rating, especially with so many tricky obstacles
Wimpy 10 – Labyrinth of Despair – now this one is truly deserving to be on this list! Not only are there multiple solutions in this level, but every solution requires a couple of tricks to get up the walls, making this level very fun indeed.
Wimpy 12 – Russian Rescue – another level deserving to be on the list, due to it being a puzzle level that requires a certain degree of strategic thinking
Timid 15 – Locked Out! –I’m sure a couple of you know by now that the locked exit/button puzzles are my favorite types of levels (although I haven’t beaten Collection Pit or Lost In Translation, sadly; the former I really want to beat). I am very glad this one made it in the pack.
Cheeky 5 – A Violation of Lemming Rights – another great puzzle level with so many one-way walls and a very tricky structure.
Medi 6 – Fallen – the LPDOS winner, and very deserving of the first place position (or Wimpy 10/12, whichever one doesn’t matter). Gotta love all the tricks used in this level.
Medi 16 – The Oddstack – okay, this one may be very difficult, but I’ve learned a lot from this level in regards to timing. Plus, this one will be four minutes long in NeoLemmix, so this level won’t be as bad this time.
Dodgy 11 – Extra Skill Required – a puzzling level that makes very great use of the pickup skills. Definitely deserving to be on this pack.
Sneaky 13 – When Only a Lemming Will Do – a fun Sneaky level, especially if you only have one minute. Lots of timing involved, making this one a challenge.
Danger 5 – Some Kind Of Lemming – a small but challenging and rewarding level. I didn’t even know that the Oblivion trick wasn’t even part of this level's intended solution.
PSYCHO 1 – Variety Day – the best Hero concept level (along with Hero Frenzy, but that can't be included).
Genius 8 – Panic Attack – of course, one of the best levels of LPII with a really great, claustrophobic design and lots of timing.
Levels not on the Top 30 that are my favorites and would have been worthy to add:
Medi 8 – Cavern of Chills – this one may look simple, but finding a way up that dirt wall requires a certain strategy.
Medi 12 – Step Up! – a great level that uses a lot of destructive skill tricks. I also liked the limited builders.
Danger 6 – Alternative Logic – you’ve managed to squeeze everything in just one minute, with the solution requiring the last lemming entering the exit right before time runs out. A gem indeed.
Danger 11 – The Warp Room – this one is your oldest level, and it may be worth adding so people will know how you started designing levels.
Danger 16 – Grounded! – my favorite “find a safe way down” level.
PSYCHO 22 – Twins – a great “find a way up” level with a limited number of builders, requiring you to use other destructive skills.
Nice 12 – Cactus Island – like On the Pier, but more challenging with a limitaton of blockers, builders and bashers that make this level more worthy of being in the pack.
Nice 17 – Lemmings Gettin’ Down – this one is intense due to the fact that you only have bashers and bombers along with a high release rate.
Cheeky 15 – To the Treehouse! – I agree with Akseli here; I had a lot of fun with this one.
Sneaky 5 – Misfortune of the Masses – a very great level; you have to find a way around the walls while trying to save the lemmings at the left at the same time.
Sneaky 10 – Drought Season – this one isn’t actually one of my favorites, but the general consensus is that it’s a very good and tricky level involving trying to solve it when you are unable to hold the lemmings back, so this one would have been worthy to add.
Genius 13 – Only a Lemming Away – I had fun with this one, it required a lot of good timing, and I felt the solution was clever.
Timid 12 – No Floaters, Guaranteed – this one’s so intense due to the high release rate and that radiation object in the middle. It’s also slightly similar to Cactus Island because you have to find a safe way down without floaters (but you have plenty of skills). There’s also multiple solutions in this one.
Dodgy 3 – Flea Market – one of the most original levels I have ever played. A level that can only be solved by knowing which pickup skills to use? Clever indeed.
Dodgy 7 – Experiemental Materials – agreed with Akseli and Nepster. This one should be in the collection pack, despite it not making it to the finals. It’s fun finding a way around the one-way walls.
Fierce 3 – The Soft Scale – this one required a lot of tricks to solve, but it felt very rewarding for me once I figured it out. I also made good utilization of the updraft.
I recommend adding Dodgy 7 "Experimental Materials" if you plan to add two more levels, partly because there aren’t a lot of LPIII levels in the list, and partly because this level is also Akseli’s and Nepster’s favorite. Cheeky 15 "To the Treehouse" is another strong consideration.
