I've been going nuts for myself trying to decide between the DL4 and the Boss DD-20. As anyone can figure out from reading the review, all three pedals sound great, but have found ways to be extremely different from one another. You can't just say any one is better than the other -- it's totally going to be an issue of what kind of music you play and what kinds of delay sounds you like.
My problem is that I tend to prefer the sound of the DL4 but the interface of the DD20. I suppose I could always put one of each in my pedal board, but that's a bit overkill since nobody besides myself will really notice the subtle differences.