If price is not a concern I would suggest purchasing all four.
You then have two options,
1)perfrom extensive testing to see which works best for the dovetail needs you have
2)Or have them all sent to me. I can run independent testing on all four models, prepare some spreadsheets of their relative strengths and weaknesses, then send you the winning model.
Consider another, quite different approach - The JoinTech Cabiinet Maker System. It's a router table with a precision positionable fence (as in adjustable in thousandths) that uses paper templates to index where the bit will cut. Cut the tails with the part flat on the table, the pins with the part square to the table and 90s to the fence. Has the advantage of having a nice, precise fenced router table - which you'll probably end up getting anyway somewhere along the line. This one does that exceptionally well as well. Split fence, replacable zero clearance inserts, built in dust collection in the fence, uses normal, readily available router bits, rather than "special" bits or collars, . . .
Wanna make sliding dovetails of ANY length AND fine tune the fit? This'll do it. Want to do perfectly fit lock miter joints - this'll do it (with the normal trial and error set up - unless you also get the set up block) Check it out.
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I've got enough stuff that I have to find a place to store when not in use (but I still acquire another "where the hell am I gonna put this thing?" when the "gotta have one of those!" moods hits me)
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