The March issue of Wood Magazine has a review of Through Dovetail Jigs. They like them all of course. They say they are idiot proof. That last statement is bogus. A hammer is not idiot proof. Anyway, I just bought my third dovetail jig and I would like to give my 2 cents worth.
My first jig was the Leigh. It worked great and was easy to use. Those who say it is not easy to use must not have seen the Leigh manual. It is the best manual I've ever seen for anything I've ever bought. If you can't read, the pictures are great. But I've given the Leigh away because it didn't do what I wanted it to do. That's right, the most highly rated and most flexible jig didn't do what I wanted it to do. I wanted a jig that supported the router and workpiece really well, controlled the dust, and not use bushings. I never liked running my router over those fingers without tipping. And I ate a bunch of sawdust which does bad things to my nose.
My next jig is the Akeda. It really is easy to use, supports the router extremely well, and the dust is controlled. You can leave the router on the jig hands off. However it still uses bushings. The claims that the Akeda does not require any adjustments are bogus. Why do they sell the over and under-sized straight cutters and bushings? The Akeda uses different size dovetail cutters depending on the wood thickness. I've found some of the Akeda cutters work better than others for getting a good fit. In fact, two of the dovetail cutters don't work at all for me. I've also bought the Whiteside bits for the Akeda. They are much better bits. I am satisfied with the Akeda and will keep it. It does half blind joints much easier than the Leigh. It is not as flexible or adjustable as the Leigh, but you can vary the pin spacing in increments of 1/8 inch. Actually, I like the fixed 1/8 inch spacing better than the variable spacing. It is easier to remake a part in the future because you can set up the jig exactly like it was when you first made it.
This week I purchased my third dovetail jig... a Keller 1500. The Keller has fixed 1 1/8 inch pin settings so you have to design your project around that. The Keller uses a bearing on the cutter so no bushings. You can also turn the Keller upside down and use it on a router table. This is the way I'll be using it because it gives me the ultimate control of the workpiece and router while eliminating all the dust. But I would not keep the Keller without modifying it. I modified the Keller by installing a T-Track in the bottom of it. This allows me to place an edge stop to position the workpiece. But due to the layout of the Keller template, the edge stop has to be offset for the pin workpiece. The offset is 9/16 inch which is half the pin center to center distance. The alternative is to mark the pin placement on the workpiece after cutting the tails and then visually place the pin workpiece on the template. Too much chance for errors and inconsistent results. I'm pretty fussy about getting consistent results from my tools and jigs. That's why I only buy Craftsman contractor table saws. Just a little joke there. Finally, the manual is not that great. It's a good thing the jig is so easy to use. The manual says the jig template is 1/2 inch thick, but it is really 17/32 inch thick.
There is no best dovetail jig. But I got what works for me.