(Just chiming in... again!)

I've spent the past year experimenting with several different engines for my game...
- Blitz 3D
- Cipher Engine
- Torque
- 3D GameStudio
- DarkBasic Pro
(and a couple of others I can't recall at the moment)
And I've finally settled on Truevision3D as my engine of choice!
There are 2 basic reasons for my conclusion:
1) I do most of my development work on my laptop. And while my laptop is medium-high on the list of capable laptops, it still falls far short of my desktop in terms of performance. My laptop runs Windows XP Pro with a "2.8Ghz" CPU (although it runs around 908Mhz) and 512mb memory. And TV3D still manages to deliver frame rates well above 60, even when lots of things are going on in the background! (My desktop usually delivers frame rates in the 200-300 range, sometimes topping out over 1000!) Needless to say, this is quite impressive for laptop performance, something the other engines can't quite accomplish!
2) TV3D is fully .Net compatible so I get to use my favorite language of choice, C#. With the other engines listed above, I either have to write my own DLLs to interface with the engine or use the included programming language. I don't want to start any flame wars, but some of these "languages" leave much to be desired. TV3D really gives me all the power I need but doesn't restrict how I'm able to use it.
In short, TV3D is what I want. Now I can comfortably work on my game without having to learn new scripting or programming languages, knowing TV3D can handle (almost) anything I throw at it!
Keep up the good work!
PS -- I can't wait for 6.5!