We carry the RME ADI-2 DAC, and I use a Pro version myself. It's an extremely good sounding AKM4493 implementation, but the UI and features are intimidating to people who are used to / prefer simple audio electronics. I'd say the ADI-2 has been popular for a long time now due to its performance-to-cost ratio.
Couple of caveats though. If you don't get comfortable with navigating the UI and understanding what things mean, you might accidentally change a setting and not know how to undo it. Also I found the maximum gain setting caused audible distortion for signals close to or at 0dBFS, although that may have changed in a firmware update.