I didn't find 'Hello, Goodbye' to be one of the easier ones...
Though I'm somewhat sceptical as to Dullstar's solution, I haven't even come close to achieving what he described.
nope. (Actually I don't recall seeing a "modified" version. I haven't found any solutions other than the pillar backroute though)
I posted it here:
http://www.lemmingsforums.com/index.php?topic=218.msg6538#msg6538Just in case you want to give it another try
For reference, here's how I'd evaluate my second pack if I had to:
geooPk11: Trading and Cooperating
2: The Way Up
3: Prepairing their ways (if not for the backroutes...)
...
10: Twice the same (concept horribly executed)
'Follow Me' and 'Palace o/t once-hacked Lemmings' are pretty bad as well, the former being a backroute mess, and the intended solution of the latter is ugly to execute just for the sake of using a glitch.
Some more:
ClamSpam011: Hello, Goodbye (I remember how this one had tseug and me stumped at first)
2: Dig This!
3: Catch Your Death
...
10: Escape from Alcatraz!
ISteve101: The duct rise lemmings.
2: This is a gate level
3: The Decent Descent (or 'Empty Space is Hardly a Waste' if it wasn't for the backroutes)
...
10: I am I.S. (Part 2)
(This is another pack where even the worst level is still good).
I don't remember this pack too well, but at least I'm pretty certain on the first place:
BulletRide21: Final Call
2: The Quiet Place
3: Jotun
...
10: Deep Six (Part 2)
Also thought I could list Fleech/SgB's levels, but I remember too little to properly list the best ones, I remember they were hard, really good and had many backroutes, resulting into an eternal game of fixing and finding new ones.