I'm pretty much like your friend. I do 3D Professionally and I game a lot.
It sounds like your friend is more into Game Content Creation rather that Film/Commercial type content. If that's the case... well actually no matter the case for someone on a budget forget the Quadro's and FirePros. I personally will never buy one of these and have been using gaming cards fine for the passed 10 years. When you usually render for game content it's "baking" textures or maps to use in game engines. At this time, it is mostly done CPU side.
OpenCL is still not utilized to it's potential now, everything is CUDA if you plan on GPGPU rendering (Octane, RedShift, Vray (big name 3dsMax renderers)). So yes, nVidia over AMD for this stuff as well. Which is unfortunate because AMD cards curbstomp nVidia's software limited cards in proper openCL benchmarks like Luxmark. A renderer like Redshift which is coming soon to 3DS Max(summer) is set up to be out-of-core design so it isn't reliant on your video card memory as much as Octane and others.
For Vegas/After Effects, does he digest a lot of 4k Footage? Does he do large compositing jobs? Can you be more specific with what your friend does?
I think those parts are fine, maybe push for a 6C/12T CPU if it's in your budget and at least 16 gigs of ram if he's pushing over 4k textures. 780 TI will be plenty.
I mean people do this stuff on years old MacBooks and Laptops. Maybe if he's more a texture artist, invest in a good Wacom Tablet/Cintiq. Bleh need more info.