First, the most important features are those most important to you and what you want to do with the jig. That alone can have a huge impact on what jig is right for you.
I want the versatility of being able to space the joints as I like as I think they look better when spaced according to the piece being worked on. That alone limits the field of contenders.
I bought the Leigh D4 and remain very glad I did. It cost more, meant I had to wait a while to get it, but it is working great and doing at least what I wanted, often more.
The Leigh is very well built, comes with the very best instructions in the business, is easy to use, accurate (stress this point!) and repeats better than anything I know of.
I hear lots of comments about how long it takes to set the Leigh up. Maybe I am doing it wrong but once I got used to it, I can set up and cut dovetails in far less time than with any other jig I have used. I recently did a jewelry box with custom-spaced dovetails that took less than half an hour to complete from the time I brought out the jig, including setup, cutting the joints, testing them and putting it away.
There are lots of jigs on the market, and all of them serve a segment of the woodworking community or they wouldn't be selling them. You have to decide which is best for you now, and more importantly, in the future. Your range of projects will likely grow more complicated, making the ability to custom design dovetails more important. that is exactly why I went to the Leigh, and why I should have bought it in the first place. That way I could have saved myself about $400 that I spent on other jigs as I worked my way up to the Leigh.
Look around, check them out and find the one that fits your situation the best. It might be the Leigh, maybe not.
The woodhaven unit is a good jig. It allows two sizes of tails to be cut from a single template, it uses a bearing guided bit which is easier than a bushing setup, and this model also allows it to be used inverted on a router table too. I have one of these and I consider it better than most all the jigs of similar ilk.
However, as Tom mentions, there are others to consider. The “problem” I have with jigs of this type is that they are finicky to set up and produce a joint of anemic proportions. If I were shopping for a jig these “cookie cutter” types would NOT be my first choice, I would rather have a through type template jig or if budget allowed one of the better variable jigs like the leigh.
I have a few dovetail jig related article on my web if you are interested.