If we are going to make these comparisons, shouldn't they be like this:
Corners First = DOS. Hardly used anymore and those who still use it are veterans that know there are better systems around. However, after using a system that you know inside-out for so long it is hard to leave it.
Layer-by-layer / Beginners = Windows 95. Old system, was used by many people. It wasn't very advanced, but it was easy to use and some slight improvements were added later that made it a little better
Keyhole + 4 look last layer = Windows 2000. An improvement that could be used to get a much better understanding of the system, but most people just skipped this and went straight to....
Fridrich = Windows XP. Used now by most people, pretty fast, nice and compatible upgrade from previous systems. It has been around for a while and almost all flaws have been ironed out. However there are some fundamental problems that most people don't see but are well known by others.
ZBF2L + ZBLL = Vista. Better in theory, but requires more resources and isn't as well supported. Some people are making the switch, others that have made the switch return to their previous system.
Petrus = MacOS. It has gone through several several changes, but lately more and more people are making the switch and getting good results. It has a very solid base and is very optimised for the type of hardware it is run on. For some reason many of its users are a bit fanatical and try to convince others how perfect their system is.
Roux = Linux. It is new and has lots of potential, but not a lot of info is available. Sometimes you meet a user and they are always enthousiastic about their system and they tell you about all the freedom of use and different tricks they found. The system is still under high development and its founder is a big advocate in the community.
Heise = Linux from scratch. Extremely optimised, but using it requires huge amounts of dedication. Everyone questions its usefulness, but everytime you see it in action you are impressed.