If one had to pick one of my favorite digital synthesizers, the Roland D50 would be it. For some reason, the Roland D50 has an unusual warm sound, uncharacteristic of most digital syncs even today. The Roland D50's programming area is a big mess, but even the default patches are standouts. You can not only create smooth, realistic digital instruments with this keyboard, but some unusual analog pads and effects. It certainly is one of my favorite keyboards out there. The big downside is the programming complexity, and the keyboard itself is not the best out there.