It depends on what you are producing.

For school projects or pure research-based design, Rhino has the features and commands to model nearly anything, whereas Revit is quite restrictive in designing new systems and detailing.

Grasshopper has the features necessary to use data in design and visualizations, and I only see our profession becoming more dependent on contextual data. In that way it affords more opportunities to take part in advanced design. 

For high-volume office production, it probably doesn't matter one way or another as long as the office workflow is set up to utilize the software correctly.

I don't think there's really a best software to use. It all depends on what the individual or firm is trying to accomplish. Rhino is great for design flexibility, and grasshopper enables parametric functions to be applied to that design process. However, that work flow lacks efficiency when producing construction documents. Revit, on the other hand, is super efficient when producing documents, but has built-in limitations when it comes to design. You can work around those limitations by adjusting parameters, but then it can become inefficient when dealing with your design. 

Personally, and I'm sure tons would agree, the ideal solution would be seamless workflow between a program like Rhino or 3dsMax and Revit. It would be amazing to design a building in Rhino, export it to Revit and be able to tag, cut and detail everything as if the model was originally created in Revit. However, that's just not the case since both applications use different modeling formats; Nurbs vs Polygon/Solids.

Regardless, it all comes down to preference/outcome as to which is best. 

Nicholas

can Rhino be developed for collaboration? or how would you set up a collaborative environment.

Stepped away from my computer mid-reply, and Nicholas took the reigns! Cheers!

Rhino has an established user base, is powerful, and relatively easy to learn. Grasshopper give it the ability to cycle through many design options quickly. Personally, I prefer it as a design tool for this reason.

Revit now has the concept modeling tools, which go a long way to address it's inferiority as a 3D tool for design, but these are relatively new and not well-known. Having played around with them, they have a lot of potential and will probably eventually be great. Right now, though...not so much.

Rhino supports Worksession sharing among several collaborators. It is built into the program if that is what you mean.

Remember that Rhino is the base software, but there is a whole world of plug-ins for Rhino and Grasshopper that give it increased abilities.  Rhino is owned my McNeel, which is a private company, but treats Rhino as more of an open-source product, meaning that there is really no limit to the number or types of programs that can be developed to run with Rhino.

If you are a programmer or very computer savvy (I think I remember you are Xenakis) you can create custom Macro commands, and even build an entire skin on top of Rhino. (Think how the Ghery software is built on CATIA), and it accepts VB, C++, and Python scripting.

Also, when you post questions on the Rhino or Grasshopper forums, they are usually directly answered by the software developers themselves. AutoDesk will never have that kind of support.

Rhino is an amazing design tool, Revit is an amazing production tool.  Autodesk is trying to get at some of what Rhino/Grasshopper does via Vasari, but they still have a LONG way to go.

I come from a bit of a software development background, and I have to say that Nicholas is totally right: the flexibility and "openness" of Rhino is amazing.  Its ridiculously powerful and intuitive software.

By constructing things in Revit's concept modeler, I can do sweeps that mimic  bi-rail

to some extent - it's a trickier than in Maya or Rhino - then you load hose forms into the Revit project and slap architectural elements to the concept/massing surfaces - 

Xenakis, it seems as though you are looking for the flexibility of Rhino without sacrificing the BIM capabilities of Revit. Have you tried Geometry Gym or Visual Arq plugins for Rhino?

I will try those out - If this works - then It may be possible to use the tools you mentioned in architecture offices- last year I was working on these quadratic acoustic walls for BING concert hall at Stanford - I modeled them in Maya, then imported the surface into Revit as a mass, then we would rig sweep paths for the metal stud frame - it was a lot of work   -I  think using your process may have yielded a more controllable solution. The office that did the original design did in fact use Rhino.

The benefit of Rhino for a project like that would be:

Pachyderm (Acoustics plug-in) or Grasshopper Acoustics > Surface Design for walls > Generate parametric structure in Grasshopper/ Visual Arq/ Geometry Gym > Export takeoffs into Excel > Export production documents for waterjet/ other processing as line drawings.

You never leave Rhino, everything is integrated, everything is parametric and one change propagates through the entire model.

no no no... trace paper and pencil is still the best design tool for me.   CAD tools are only when i've finalized on my design and need to get into details and dimensions

"no no no... trace paper and pencil is still the best design tool for me.   CAD tools are only when i've finalized on my design and need to get into details and dimensions"

Is this not true for everyone? Even your most ardent user of the computer has at some-point  somewhere, an initial sketch. The only variance I have seen is when they take the sketch and attempt to make it "real" (terrible term, but I lack coffee). That could mean cad, bim, or even the measured pencil drawing.

To address the original topic: 

Learn both Revit and Rhino. Rhino+Grasshopper is very fun, but can be frustrating as a learning experience. I have yet to have fun with Revit, but it works well for what it does. Yes, I have fun with Autocad. There is a rhythm to Autocad, that Revit and Rhino+grasshopper lack.

Rhino inside Revit, its a plugin used in some firms.