First, you're welcome :-)
in the usual ng's. Okay, so caveat given...
All your choices give you Glide support, which is still a key, especially in
the sim world. Some here will direct you towards the rendition-based Hercules
Thriller which has unique support in the racing sim genre thanks to Sierra.
However, I consider it to really be a niche product now. 3dfx is the way to
go *unless* all you want to play is Papyrus sims.
As to your options, tough choice.
Banshee pluses:
16MB for high texture games
1024x768 (higher?) support
Somewhat faster in non-multitextured games due to higher clock
3D in a window
Greater color depth??
Single card solution
semi-AGP (FWIW)
Minuses:
Are the drivers mature?
Single texel
V2 pluses:
twin texels for multi-texture supporting games
Can Scan Line Interleave with another V2 (Guillemot offers two for $230)
It can do 1024 in some games (non z-buffered), but not all.
What neither has:
32-bit depth, (real) AGP support, maybe some other geegaws that the TNT has
What would I do?
I'd probably get a V2 12MB since they are cheap enough right now, and perhaps
consider a TNT as a future upgrade for your Diamond 3D if/when those extra
features become meaningful. AFAIK, none of these features is really relevant
in present sims.