Is It Better To Have A Hard Or Soft Guitar Case?
Do you want to protect your guitar from bashes and smashes in addition to dust and humidity, or just the latter? That's the main question to answer when wondering whether or not to buy a hard case or soft case for your guitar. Both protect from the elements, but hard cases are vastly sturdier and offer far better protection — with some caveats.
Ideally, any serious storage of a guitar ought to involve a bespoke, hard case with some kind of soft, even fuzzy interior, and a snug fit is best. This will protect the guitar from being stepped on, crushed, etc., from the outside, and protect it from clacking against the inside of the case when jostled. You also want to keep the guitar inside this hard case when it's not being used, not on a stand where it's exposed to dust, light, and humidity that will eat away at the wood, strings, pickups, and other delicate parts over time. Think of long-term storage, travel, or moving house, too. You'll need to stack the guitar, lean it against things, slide it into place, and so forth — all of this requires a hard case unless you want to destroy your instrument. Furthermore, hard shells have actual locks and not just zippers.
You don't have to ignore soft cases altogether, though. They're definitely lighter and easier to carry, so they can be better for gigs or short-term storage in a safe spot. Just remember that they're basically just dust jackets that offer minimal impact protection.
The ins and outs of hard cases
The better you take care of your guitar, the longer it'll last, even up to hundreds of years for a perfectly preserved acoustic guitar — it's as simple as that. Hard cases are the first, last, and ultimate guitar protection, and vastly superior to soft cases in every way except weight and portability. Some guitars come with their own, bespoke hard case, perfectly fitted for the specific guitar in question, though this is sadly less common nowadays than it used to be. Complimentary soft cases are still customary, though. This means that you should go into a guitar purchase expecting a case to be part of the purchase, so you can test it out first-hand.
Unfortunately, hard cases can be as expensive as cheaper guitars, such as a Fender Stratocaster Squier. You've also got to make sure the case fits your guitar in a way that won't let the guitar smack around against the interior. More often than not, the best you can do is look for cases that match the make, model, or general line of your guitar, like Martin acoustic cases for Martin acoustic guitars; cases will always be split into acoustic and electric types.
Technically minded nerds in the audience can also investigate case materials if they want, from ABS exterior shells (pretty flimsy, but alright) to carbon fiber cases (the tough stuff). Check the thickness and foam/plush interior, too, to make sure it's thick and non-abrasive enough.