Also, along with the Adam and BobbyC sclupts that I posted some pictures of, noone in their right mind can argue that mokneyrobotmaster's customized DX head is not better than the standard version.
I think you need to understand that there are a great many different criteria one can use to determine if one head is "better" than another head. There are many reasons one could legitimately use to determine that the stock DX head is better than any of the customs you use.
For instance:
-Which is "better" for a consistent multi-figure display?
A custom can stand out as being very different in make than stock figures - both for the materials (silicone vs. plastic or "real" hair vs. plastic hair) and paint. One might argue that on its own a custom Joker looks better than a stock DX Joker - but next to a bunch of other HT releases (like DX Batman, OC Batman, Two-Face, Bank Robber Joker, etc.), consistency in the aesthetic makes the stock head "better" than the custom. These characters all come from the same line of figures and the same movie - it only makes sense that they should appear visually consistent in make.
-Which is "better" for a self-consistent figure?
A custom headsculpt made of silicone looks more "real," but if it's on a Hot Toys body (with plastic gloves, shoes, etc.), it doesn't look consistent with itself - part "flesh real" (the head) and part "plastic toy."
-Which is "better" for multiple posing purposes?
Plenty of customs or repaints (of non-DX heads) do not feature the PERS of the DX head - so you can't pose nearly as many facial expressions or positions. If this is an important criteria for you, one could easily say the DX head is the best head.
-Which is "better" for an "action figure" aesthetic?
Personally, I don't like "real" hair with individual strands - I think it makes figures look more like "dolls" and less like "action figures." (I don't want to argue about definitions or differences, but if you read on, you'll see how that distinction is important for some of us).
For someone like me, the stock DX head is better because it does NOT have custom strands of hair. Part of the appeal of these figures for me (and others) is the connection to the hobbies of our childhoods. We collected and played with action figures (like the Kenner "Batman Returns" line), and this is a way of connecting back to and embracing that part of our past. Those figures had plastic hair, which is one of the distinctions we had between our toys and the Barbies of our sisters. It might sound stupid, but that's the fact of the matter - having "real" strands of hair serves to divorce us further from the hobby of our childhood, rather than strengthening the bond.
-Which is "better" for your wallet?
You might want to judge or compare a given set of heads or figures on its own, separate from the reality of their cost. But these are actual, physical objects that have to be paid for. The reality is that for some, having a more expensive head means having less figures (and a smaller or less complete collection - certainly something important for someone looking to maximize the aesthetic of their Batman collection as a whole). Or maybe it means not eating a full meal or going to the movie theater less often.
Each head has various qualities - the paint-job, the poseability, the quality of material. The monetary cost is just as much a real quality that the figure has as any of the others It's completely legitimate to say the DX head is better because it's cheaper. Many of us have to divide the qualitative aesthetic value of a head by the quantitative monetary value - and the DX might come out on top when looking at that ratio.
Customs might be "better" and "more accurate" for your purposes - but plenty of people "in their right mind" can logically determine that the stock head is better. You can't objectively say that any given custom is "better" than the DX. I would just caution you to consider that.