I think the best bang for the buck would be a Its George 2x4. You can find them in the ForSale/Wanted for $200 or less. There hasn't been a new one made in nearly 15 years, so the ones you see are either new old stock, or used. The used ones seem to hold up well to abuse.
If you have the money, invest in a Jack Justis. I've seen old ones (tubes) for as low as $300.
Some new it's George cases were made a couple years ago. Mike Gulyassy was going to be the distributor but that all kind of fizzled out for some reason. Don't see many 2x4 It's George cases for less than $200 used. Acedonkeyace has a couple for sale right now and he wants $250+ for them.
If one like that's type of case then GTF is a great choice. The GTF KopyKat line is upholster grade vinyl and indistinguishable from leather, done in the Fellini style with hand finished ends for just $250 or maybe around $200 at Seyberts.
A decent JJ-Tube for $300 would be a good buy but they very rarely get that low. A good comparable case which still uses tubes are the Dennis Swift cases. Those are around 300+ new if I remember right and Dennis has a quite a variety of choices now.
Regarding the OP's request I don't think that there is much on the market that offer's more protection than our interiors in a top-loading case. That coupled with the other details we offer would make a pretty compelling bang-for-the-buck argument in favor of the variety of cases coming out of or designed by my shop.
This basic nylon case is fairly plane jane but it's pretty sporty as well, super tough and offers better protection than the brands you mentioned. That's just the facts. Of course how much protection a person needs for their cues depends a lot on how much care they are willing to take with their case. For most folks less than what we offer is enough as accidents that would damage a cue while it is inside the case are not everyday things.
For me, before becoming a case maker, I went to hundreds of tournaments before my (other brand) case was knocked off the table and the cue shot out of it. I probably laid my case on the corner of the pool table a hundred times before that accident occurred. Still it was a $1400 Schon that I LOVED and it cost me a bunch of money and a big hassle sending it back and forth from Germany to the USA to get it fixed.
So essentially I ended up fixing that problem by making the world's first padded interiors for top loading cue cases.
For me everything else is fluff. Looks are meaningless to me. That's all jut personal preference and some people like It's George's look, Fellini's look, Justis, Whitten, etc..... I just care about the part you can't see and make sure that part is protecting the cue as I think it should if you just spent a decent amount of your savings on it.
Because at one time, as an airman in the Air Force, I did spend a good chunk of my savings on my dream cue. And when the case failed me I rebuilt it to do what I thought it should do.
Thus I am sensitive to "bang-for-the-buck" discussion when protection is part of the discussion. Want to talk about beauty, prestige, reputation, collectibility, then we probably don't do so well against some other famous brands. Although by now we do have a decent portfolio of custom work to put into any beauty contest. ;-)
Anyway, that's my thoughts on value in cue cases.