They're fairly similar in terms of features. The Dash does have the overall edge though. So really It comes down to form factor. Which do you prefer? Keep in mind the dash has a nicer screen, a qwerty keyboard, and is much thiner. The SDA, however, isn't as wide.
I had the SDA not too long ago and I would recommend it. I'll probably buy another one of these days because you get a lot of phone for the money. You can't get many phones with wifi for just over $100.
