+1 for the Leigh jigs. I have the D4R, which is my 4th (and final) way of cutting dovetails. I tried several other dovetail jigs before getting the D4R, but was never happy with the results
that I got from them. Now that I have a D4R, I have no need to look further. I am very happy with the results that I get from this Leigh jig.
Having a jig that you set up once to cut both the pins and tails, makes a huge difference because they must match "perfectly". The D4R does this exceptionally well, yet lets you create randomly spaced dovetails that look hand cut, and once you have the jig set up, you can quickly rout the same pattern on as many parts as you want.
I also have their FMT Pro jig for mortise and tenon work. It also lets you make perfect fitting M&T joints with one set up to do both the mortise and tenon. Leigh CS is the best you will find anywhere, and their manuals are the best as well.
Incra jigs will do dovetails, but they do not have the versatility to easily make random width spacing. You have to position the fence to specific guide marks on a guide strip for each pin and tail cut and I haven't seen any of their guide strips that allow doing any random positioning, although you could maybe create your own guide strips to do this. A PC program that was created by one of our members (furboo ?) may be able to help you do this but I have no experience with it.
Go to the Leigh jig website www.leighjigs.com
and watch the videos on their dovetail jigs. Their manuals are also available for download, so get a copy of the D4R manual and read it. I think you will quickly realize how well their manuals are written. Yes, cutting dovetails is complicated, but their manual will have you making a near perfect dovetail joint on your first try.