Pretty simple. At the $100ish price point, who wins? I play garage rock, and my rig's in my sig.
Maybe try them out? I imagine the DD-3 would be more versatile and controllable. Though I don't own one, I tried the Echo #1 once and though it was pretty good, I could only mess around with it for a minute or two and didn't get the full range of the pedals delay ability.