The best value for me, of all of the headphones that I've owned, would have to be:
R10
HE90
K1000
Honorable mention:
PS-1
HP-2
Qualia 010
L3000
Think I'm crazy? Consider this:
a) Each of these (top 3) headphones has appreciated significantly in value since I purchased them years ago. Were I so inclined, I could sell any one of them and make a substantial profit. Same is true of the PS-1 and HP-2, and I'd probably make some money on the Qualia 010 and L3000 as well, although not nearly as much as with the top 3 listed.
b) Each of these (top 3) headphones represents a true "end of the journey" in terms of any desire I might have to "upgrade". Thus, had I simply bought these 3 headphones from day one, there would have been no need for anything else.
Had I done this, I would have had what I regard as the 3 "best of class" headphones ever produced (dynamic, electrostatic, and the K1000 being in a class all by itself as 'ear speakers'), then enjoyed them for years on end, and eventually sell them at a profit (even after adjusting for inflation). No time wasted on inferior sound; no hassles or financial losses from entering and existing the upgrade market countless times; no stressing about, "if only I had X, Y or Z" because you would have all 3 from day one.
But of course that was then. Although I don't expect the market prices of these sorts of headphones to drop any day soon, I wouldn't expect them to rise that much further at this point either. No matter how good/desirable a pair of rare and discontinued headphones may be, there is a practical constraint on their market value, that being referent prices in the speaker world.
So I'm fairly sure, for example, that while a pair of R10's could at one point be purchased new for under $3k and may now sell for $6k, they will not likely sell for $9k or $12k any day soon, and probably not ever. That's what I meant by my "that was then" comment. In other words, I'm not suggesting that someone should run out and buy an R10, HE90, and K1000 today and expect them to keep appreciating substantially.
Yet, I do think there is a point in all of this. If you're new to the hobby and you can get out to a Head-Fi meet (especially the national meet), and do as much listening as possible, and walk away from the experience with a better understanding of what is possible. Then ask lots of targeted questions on the forum such that people will be in a position to understand what you're looking for (your sonic preferences, musical tastes, open or closed, full size or IEM, budget constraints, etc.), and then do more auditioning if possible, and as much reading as you can about the products that seem interesting to you.
All of those things are likely to help lead you down a more direct, and ultimately less expensive path, in terms of getting what you're looking for. Don't get me wrong, it most likely won't be the R10, HE90 or K1000. But wherever you stop along the upgrade path, the fewer things you buy and sell along the way, the better (at least for most people, although some people have a lot of fun with the "buy it to try it" approach and there's nothing wrong with that either if you can afford it).
