Pretty much any good hard case
I think you're taking a chance that way - I've seen enough regular hardshell cases munched in transit to learn that it's not worth the risk. An ATA case gives you an added amount of protection that is well worth the expense, though even that is no absolute guarantee.
There are no guarantees at all.
I have several friends who have flown around 15 times or more per year with their instruments over the last 10-15 years with acoustic guitars. One of them swore by her top of the line Hiscox (which are advertised with up to 6 people standing on them) until the day where it got completely demolished.
Another one uses a thick mono soft case and has had only one issue where they cracked the face of the guitar in all those years.
My last flight to Australia for a festival we put my daughter's electric guitar in my Gator Pro Go padded bag and it arrived without incident. My younger daughter taped a big note on her Mini Maton case saying
"Dear Baggage Handlers, my owner is a teenage girl who saved for a long time for this guitar and needs it to play in a music festival. Please take good care of me". The baggage handlers on the return leg wrote on it
"Done... hope the festival goes well". It's one of the few times we've flown with instruments where both guitars have arrived with no damage to the case or contents. I took the safe route and borrowed a bass from our Australian based drummer (actually a bass player) for the festival.
Talking about this with my best friend in Australia who is a senior baggage handler in Sydney I speculated that when some handlers see a hard case they assume that it can have just about anything, of any weight, stacked on top of it whereas when they see a soft case they know that it needs to go on top. He agreed that in most cases this holds true....... but he also went on to say that some of his colleagues are so bereft of common sense you can sometimes be unlucky. He mentioned one day where he went into the hold to check the loading and could smell wine everywhere. One of the team had stacked some boxes of wine, clearly marked as
"Fragile, top load only" under numerous very heavy cases smashing the bottles contained. When he asked which dips**t loaded them on the bottom the bloke responded that they were in boxes and should be ok.
So, what's the moral of all this? Doesn't matter what you do, if you're unlucky they can break just about anything.