I'm also working on Game for over 10 years now. Until 2 Years ago i mainly used 3DGS (from A3 on). The last 2 years i was using C++ with Acknex, as C-Script was just too limited for our needs. It worked, but as i'm a .Net-Programmer in my job i realized that programming in C++ is too time-consuming (compared to C#/VB.NET) and i started looking for other engines which support coding in .Net. I've tried many and bought some licences: Leadwerks, which has a great Graphics-Engine (but thats it) and NeoAxis, which i like most until now. Its just a great Framework designed by the same philosophy which i would use for my own engine and impressive Code<->Editor-Interaction WITHOUT any restrictions.
I took a look at Blade3d, DX-Studio and even Unity. These three are quite compareable in my oppinion. They all seem to be some kind of a gamebuilding-playground for me - I can't do things the way i want to do. There are nice ready-to-use-features, but as soon as you try to do something different then a good-looking fps-style-demo you need a greater degree of freedom in programming. Unity (and the similar engines) may be nice for artists which want to prototype their ideas, but these "packages" are just too limiting for complex games.
So i will stay with NeoAxis for the moment, but i would still prefer 3DGS over Unity.

@AlbertoT:
You'r saying "Never tested Blade but it seems to me that kind of bloated engine which tries to make too much for you thus losing flexibility" - i don't understand why you criticize this aspect on Blade3d if you like Unity, which also falls in this category?