From the three options you have mentioned, AutoCAD, AutoCAD Architecture, and Revit, I would only discard plain AutoCAD. Even though it has been used for so many years in architectural drawings, choosing it today as your new software will place you in some kind of technological disadvantage.
AutoCAD Architecture is an excellent program; you can get your models to a great level of detail, and it comes with the Detail Components Library, which is a very comprehensive database of 2D elements, arranged by categories. Schedules are very powerful, once you set them up. Floor plans can be drawn to perfection, no matter the complexity, with all the excellent tools provided. The main fault of AutoCAD Architecture is that elevations and sections are not fully bidirectional with the model, and also, I should mention that some features are not ready to be used out of the box, or might not be so user-friendly.
About Revit, well, you said you tried Revit 6. That was a long time ago in Revit´s life. Now we have Revit 2011, which is a very robust program. The advantage of Revit over ACA is that Revit is fully bidirectional, and is a true BIM program, where the model and the information are always related to one another all the time. A change anywhere is a change everywhere. Revit helps you to produce more in a shorter time than the other two options being considered. Revit is very user friendly and fun when it is used for the basic stuff. However, when you go beyond the basics, you will discover all its complexities and difficulties. One of the drawbacks about Revit, especially this current version, is the help documentation. Even though the information you need might be there, it is difficult to find with the new help system implemented in 2011. However, there are other resources, such as newsgroups like this one or Augi, when you need help with something that is not in the book, or in the help documents.
Alfredo Medina _________________________________________________________________ ______
Licensed Architect (Florida) | Freelance Instructor | Profile on Linkedin