You are asking for something that really doesn't exist yet, except for a CNC Router. A CNC router can do it all, but it's cost will likely exceed the cost of the rest of your shop. There is a very steep learning curve as well.
Your desire to have only one jig that will do all of what you want requires a jig with a lot of adjustments/variables that will complicate the jig. In my opinion, the best jig that will do what you are asking is the Leigh D4R Pro. It does an excellent job, and the manual and DVD for it are the best in the business. But, because of all of these features, it can require a refresher to re-learn the features that you need each time you are about to put it back into use. Still, it will do what you ask of it and do it very well, if you follow the instructions and set it up correctly.
If you are willing to accept a dovetail jig that lets you to just make dovetails and you want simplicity, then the Katie jig is probably your best choice, because it needs almost no adjustments. However, it can't do anything but dovetails.
Box joint jigs can run from the very simple that only make one size joint or the more complex adjustable jig that can make multiple sized joints. Most of these are simple in design but can be difficult to set up correctly. For a fixed and variable spaced box joint jig that is quite easy to set up, the Incra I-Box jig is very accurate and relatively easy to use. The manual and DVD for it are also very good and the I-Box jig can be used on either a router table or on a table saw.
I own both the Leigh D4R Pro and the I-Box jig, and I once owned the Katie Jig. All of these jigs will do what their instructions and advertising say they will do, and do it very well, if you set them up correctly.
Central North Carolina