I have the Duralast flex and I have to say... it's a very nice 36 tooth ratchet. I did the "spring clip" mod on mine and the action is really nice considering the tooth count. I have used it pretty hard and no complaints whatsoever. Actually, it's amazing when compared to other $20 long handle flex ratchets, or craftsman 36 ratchets for that matter.
However, the Armstrong maxx locking flex is just a nicer ratchet, but of course, it's like comparing apples to oranges because what makes it nicer is the fact that it is 60 tooth and has a locking mechanism. I also like the fact that I can throw an 88 tooth Matco kit into it if I choose.
If the Duralast was 60 tooth and was a locking flex, it would be a much harder decision, especially if the Duralast were cheaper.