Ah, the stormtrooper helmet. This is the thing that started me down The Dark Path almost five years ago.
They're all off, which is why we're still talking about it. And the differences are truly tiny; some of you will recall I measured the Hot Toys stormie helmet with digital calipers and compared it to Marmit stunt helmets.
The differences were sub-millimetre. At this scale, with an iconic helmet we've seen thousands of times, those differences translate into red cognitive flags.
The HT sandtrooper helmet gets something right that not even Marmit does -- the lower "jaw" area around the lateral tubes isn't as bulky; but of course there are other issues. The width of the earpieces isn't a big issue for me since those varied by helmet on-screen, and it gets the silhouette right for a number of screen-shots, if not for the sandies themselves, several background stormies.
There is even variance between batches of Marmit stunt and hero helmets in terms of sizes and proportions, so no consistency to be had there.
The original Hot Toys stormtrooper helmet is actually their worst iteration, relatively speaking. The HT sandie helmet gets a lot right but still bears an "illustrated" quality of interpretation rather than dead-on screen accuracy. Now MMS304 ... for some reason that one is different, and some days I actually like it best although I've generally ranked it second place. The dome is higher, and the frown is wider. A look at eBay prices shows us that would be a hellaciously expensive upgrade, though.
I recall seeing the digital renderings of the TooMuchGarlic helmet, which is truly Next Level if anything is, but he seems to be focused on the Vader helmet for the moment.
I'm almost in a position where I want to choose between MMS304 and MMS295, because I don't like collecting variants and want something definitive, but for the moment I can't bring myself to be that brutal.