We have received a lot of questions over the years as to what type of plywood is "better." Better for what purpose would be the better way of saying it. There are a wide range of plywood suited to an even wider variety of end purposes. Wood types and grades can be complex and their uses can vary among builders. There is also a lot of misinformation, opinion and rumor out there regarding plywood. So, we are going to keep it simple regarding our purposes in the road case industry.
The first thing that we can tell you is that the type/grade of plywood for making road cases is much less of an issue than plywood used in other avenues of building and manufacturing. The most important factor regarding this is that the wood is not exposed. Once the plywood is fitted with an exterior laminate, placed into the extrusion framework, glued & riveted, and then finished off with corners & corner braces, the wood pretty much becomes a secondary feature. That's not to say it is okay to use unfinished wood, particle board, OSB, etc. in place of a decent plywood. However, you don't need to spend money on woods like Birch, ACX, etc. You also don't need hardwoods (other than for your caster boards). A Lauan, pine or fir sanded on both sides will work just fine for 90% of case needs. Birch is better for cases that will be used under the most extreme physical conditions, including repeated high moisture or humidity environments.
Having said all of this . . . our standard plywood is the most affordable option, and perfect for the majority of your case needs. If you feel that you need to ratchet things up a bit, then our Birch is the ticket.