My next battery purchase will likely be the itaste vv v3. Basically, because it's small but I think I'll be happy with something that doesn't roll around.
I can't commit to any particular tank but the T3D and T3 mini are both pretty cool and very workable as far as my experience goes. Neither are exotic at all but I don't see people pushing them. . . probably overlooked because they're so similar to such a standard. The mini is hotter because it's a shorter distance I suppose. I don't notice much of a difference, honestly. The T3D is pyrex but it uses a different coil than the other T3's. So far I've used the T3D to burn through some juices I'm not too hot on so I have an unnatural bias against it but it's the simplest pyrex design I've come across and that really appeals to me. I just wish it used the same single coil heads that I normally travel with. (Hear that, Kanger! I'm talkin' to you! I'd actually be super stoked with a pyrex T3 mini. . . )
Edit: Apparently, the T3D's are not pyrex but a quick Google search will reveal several retailers advertising them as such (including one often noted as being quite reputable.) I emptied my only model to get a good tap test and it does indeed sound plastic. Unfortunely (or not. . . ), I purchased mine from a more reputable vendor that does not misadvertise their product as pyrex, so I guess I can't really complain.