So to say what "is" best is simply not going to happen.
What is best is about you the keeper. Rack systems are handy for keeping snakes alive and breeding them. Its handy for people who do not care to learn from their captives. As they are not allowed to do anything but the bare minimum. In many cases, you cannot see them anyway. Opaque plastic, etc.
If you want to enjoy the captives, then a cage that allows you to see them is nice. If you want to learn about the animals, then a cage that allows the animal to do things, climb, burrow, swim, make temp and humidity choices, etc. If you have a captive that is particularly adapted to something, like vinesnakes(have them) or greenrats(have them) or hognose(have them) or kingsnakes(fairly generalized burrower, but do climb too) Then display them in a way that allows them to do what they are designed to do.
IF your joy mainly in the owning or pocessing of a snake, then rack systems can be for you. Or if your a commerial breeder, then rack systems are for you. Theres nothing wrong with commerial breeders housing their stock in a commerial way. But consider, why would a non-commerial keeper want to do that???????
You see, the choices are out there, you can pick whats good for you. I personally scratch my head over all these beautiful kingsnakes being kept in a method they offer no beauty. Odd, don't you think?
More examples, Some people, Kerby comes to mind, are more about what comes out of the eggs. That is, if you breed this one with that one, what will result. That is something that has always driven me. Or someone like JETZEN appears to be. He may keep them in racks(I really don't know) but he hand feeds them(or at least that he what appears to do. His hand feeding is a good way to enjoy the snake and SEE it. As well as giving something for the snake to do different. You know, get out of the box every once in a while.
There is only one REAL limitation, and that is your imagination. The reason I hate caresheets is, there are only a place to start, not a place to finish. I guess I would rather hate caresheets, then hate the people who have no imagination. Cheers