Vishay/Dale, Cherry, and Babcock are all good. Some folks prefer one brand over the other but there is little consensus - I have googled it and read just about every thread. In other words, if you are buying one the most important factors are burn-in (if used) and the date on the back if you are deciding between two options. What I will offer here is a debatable ranking of the 3 and urge anyone to add to this thread or change my order: Best to Worst
1) Vishay/Dale: These guys are still in business and i think (as of 2012) are still manufacturing in bulk quantities to pinball suppliers... There have also been reports of folks getting a bad one fixed or replaced so there is a semblance customer service still available on these.
2) Cherry: No longer manufacturing and were probably the best back in the day because they seem really well-built, but the ones that are out there are generally really OLD so I would avoid because its only a matter of time before they begin to go bad.
3) Babcock: Also not manufacturing anymore, the Babcock DMD buzzes like a cricket stuck in electrical outlet and it drives me crazy! Some say the Babcock is brighter (and it oughta be with that sound) but I don't see it.... Some say they cant hear it but my theory is those inferior beings are less evolved.
I do invite anyone to add to this thread...