15mm is, for me too, just a strange compromise scale now as few manufacturors seem to offer any more detail than can be made with 10mm. FoW is a good example - they seem to have less detail than other, much smaller models.
10mm is my scale of choice. It gives the mass battle effect I am after and its monsters still offer opportunities for trying out sophisticated painting techniques.
6mm does work for WW2 Blitzkrieg Commander - but I still find myself drawn to the character and detail that 10mm provides.
I hear all that! I still have a great fondness for 10mm myself, and I've a sort-of new year's resolution to start putting out a few bits of 10mm fantasy. (Especially given SG events in 2013) But like I say, I've been knocked sideways a bit by the refreshed popularity of 15mm in some circles. Particularly with fantasy ranges like Demonworld, Khurasan, Copplestone etc.
I did have thoughts of 15mm ASoIaF meself, using Corvus Belli and Mirliton historicals. But to echo David, those were the only appropriate historical ranges that looked halfway decent to me! And from what I see in places, the popularity of 15mm is partly as a cheaper alternative to 28mm, for 28mm-oriented games, rather than epic massed-battle spectacle as with Warmaster etc.
No need to dismiss your own opinion, David. That's what I'm after, and thanks to you and everyone else for them. It's helped me to sort out my own thoughts, and realise they're more in line with those here.