I think some of y'all are confusing "why are some wings so expensive" with "are there important differences between wings".
Yes, there are important differences between wings. But, there is not a correlation between a "better" wing and a more expensive wing. The most expensive wings are not, generally speaking, any better than other wings. They're just more expensive. That could be because the brand chooses to charge an exclusivity tax. Or it could be because the manufacturer has very limited distribution, a low volume of sales, and has to charge more to cover their overhead.
I have owned 7 different wings that I can think of. Horseshoe and donut. Singles and doubles. The thing that is most important to me is that it not fall apart from normal use.
After that, the most important thing is whether it allows me to have good trim without using a weighting configuration that is inconvenient. I have had several doubles wings that would have required using a tail weight in order for me not to tip head down. Fortunately, I have found some other doubles wings that do allow me to hold good trim without a tail weight, so those wings stay and the others go or have gone.
Beyond that, different factors that apply are where the inflator and dumps are. On a single tank wing, I would prefer an inflator that is slightly offset to the left to avoid any interference with the 1st stage reg. On a doubles wing, I prefer the inflator elbow to be in the center.
On any kind of wing, I want the butt dump to be down very low and towards the outside. I've seen some wings that have the butt dump well up the side of the wing. I'm not sure how well that would work to dump that last bit of air in the wing if you are in any kind of head down orientation (or horizontal). E.g. that picture of that SportXS wing that was posted a page back in this thread.
When all those things are good, then I look for a donut shape, as I prefer that to a horseshoe, and a zipper, to let me access the inner bladder, in case I need to do a field repair of a puncture or pinch flat (which I have needed in the past), or actually change out the bladder.
The actual inflator and corrugated hose are not that important, to me, as those bits are so cheap and easy to replace. A $17 inflator and a $14 hose, both from Dive Gear Express, and that problem, if it exists, is sorted.
Fortunately (for me), I have found wings that I'm very happy with that give me everything I want. And they are FAR from being the most expensive wings out there.