I can only speak for myself. I bought a used Dewalt 788 type 1. I love it. Had to do some service on it but worth it. Not sure about the arm on the Delta but either way, you can fix that for $25 or less. Just for the sheer sake of parts I'd go with the Dewalt but I don't think you can go wrong with either one. Have you watched the Craigslist in your area? I see used Dewalts all the time for anywhere from $150 to $450. Of course, you can buy a new one for $450 most anywhere. Best of luck on the one you choose.
R