Best Case Scenario
While this information focuses on guitar cases, many of the details can be applied to other instrument cases as well.
Guitars generally come with some type of simple gig bag. But unless your guitar never leaves home, you will probably eventually find it inadequate for your needs. The first step in purchasing a new one is to determine what kind of case you need.
General types of cases include soft (gig bags), hard, hybrid (combining hard/soft features), and flight cases. Gig bags have the advantages of being lightweight, inexpensive, and they often have pockets to store accessories. However, they usually do not offer much protection against bumps and bangs. Features to look for are padding, neck support, detachable shoulder straps, backpack straps, thick durable material, and sturdy zippers.
Hard cases, though bulky and expensive, offer more protection from bumps and bangs, and also additional protection from the environment. Plywood based cases tend to be the less expensive, heavier option, while more costly polyethylene injection molded or fiberglass cases are often lighter. Look for features like sturdy latches and hinges, storage compartments, soft padded interior, sturdy comfortable handles and straps, and built-in wheels.
Flight cases are suitable for long trips where your guitar will likely be loaded in a truck with other equipment or as baggage on a flight. Look for the hard case features listed above, plus extra sturdy latches and hinges, a comfortable and sturdy handle, reinforced corners, and custom-fit foam padding.
If you plan to shop local music stores, bring your guitar along. If that’s not possible, or you are shopping online, note your guitar’s exact make and model and take a picture of it. Gather these measurements—overall length, neck to end of headstock length, body depth, upper bout (widest part of body above waist) width, waist (narrowest part of body) width, and lower bout (widest part of body below waist) width. The trick is to get a snug fit. An ill-fitting case that allows your instrument to shift around will likely cause damage.
GIG BAGS
Gig bags have come a long way with many makers creating bags with protection features like neck cradles and foam impact panels once found only 
in hard cases. Economical and easy-to-transport, look for features like multi-layer foam, backpack straps, and comfortable grips like those found on Reunion Blues gig bags.
TRY THIS: Reunion Blues RBX Series
Electric Guitar Bag
HARD CASES
Today, hard cases are made of a wide variety of materials—plywood based, injection molded synthetics, fiberglass, etc. Plywood 
cases tend to be a less expensive but heavier option. Other materials offer easier portability at higher costs. Fiberglass cases, like this one from Price, offer sturdy protection in a reasonable weight.
TRY THIS: Price Classic D Synthetic Case
HYBRID CASES
These cases have amped up protection features, but are still light in weight. Look for one-piece foam cradles, waterproof exterior,
sturdy zippers, and organization features like music and accessory pockets. This case from Bam features a high resilience injected foam insert and weighs just 5.5 pounds.
TRY THIS: Bam Performance Case
FLIGHT CASES
Today many flight cases are made of lighter weight injection molded synthetic materials. Look for TSA approved latches and locks, seam gaskets for environmental protection, glide wheels, and comfortable handles, like SKB’s iSeries.
TRY THIS: SKB iSeries Watertight Flight Cases
