OK, I'll take a cut at it. IMHO, I think it depends on what your objective is. For high density storage, the plastic racks that IGT delivers the strikes to the casino in are quite good. They each hold a lot and they stack nicely. They are also inexpensive, as you can sometimes talk a casino cashier or slot tech into giving you one if you've won a lot, or you can get them from other dealers/collectors. The problem with them is that they are not particularly good for displaying and viewing strikes. They are pretty heavy when full and it's a pain to move big stacks of racks around to find the one you want.

Another high packing density system is to use the cardboard squares with the clear plastic to cover the strike. The ones I've seen have been taken out of the plastic case that the strike comes in. I don't know why anyone would go to this much trouble, especially since they don't provide as much protection as when the strike is left in the plastic case or an airtight. I guess the plastic sheets provide a better view of the strike than a scratched up plastic case, but I think a new airtight would work just about as well. Perhaps better than the cardboard would be the plastic flips, which can also serve to protect the plastic capsule.

Some people like the Dansco albums. They display each strike nicely, and you can usually find the one you want quickly if you've organized the albums. You have to take them out of the plastic capsule to fit them into the precut holes in the cardboard, but some collectors claim that the plastic sheets work well in terms of preventing them from tarnishing/toning. You can also write notes on the cardboard sleeve. They are somewhat expensive and require some work especially if you want to insert a strike in between two others on a full page. Then you are playing musical strikes.

A less expensive but less elegant way to achieve the same effect as the Dansco albums would be to use the plastic pages with individual 2x2 inch pockets and a generic loose leaf binder. But the strikes can fall out if you tip the album, unless you use tape on each one, which ruins the beauty and visibility.

If you want low density storage but a great display, you can order wall frames from Tiny Treasures or Cassidy Frames that can hold a few or lots of strikes. They are really nice in terms of showing off a collection, but are expensive for mass storage and take a lot of wall space if you have a lot of strikes. Plus, you don't easily see the other side of the strike unless you install a clear sheet of hard plastic on the back side of the frame.

One other approach I've seen are the boxed trays with the compartments and glass tops. These are expensive, but let you see a lot of strikes at a glance. I think they are used primarily by dealers, but I could be wrong.