No easy answer other than use a brand and model that has worked well for yourself or other users. The hard drive drive itself is usually not the issue. Incompatibilities often are the result of the USB interface - controller in the external enclosure or additional selling features that are not not part of the USB 2.0 standard. Be aware, even the same brand and model can use different components and patches in different production runs.
Most major brands have tremendous inventory of identical builds and we have noticed less problems with "name brand" external USB 2.0 hard drives. Also, we have had great success with generic enclosures with a quality hard drive. The generic enclosures usually are compatible with everything and do not include the extras like one button back-up, mirroring, etc. that can cause compatibility issues with DVRs. Often these extra features can be disabled with management tools provided by the manufacturer.
Most complaints of incompatibility issues are linked to drives larger than 500GB, features such as auto back-up, one button back-up and sleep. The most frequent complaints of lost recordings, gibberish file names and stuttering playback and receiver lock-ups while initiating or saving a recording result from drives not being formatted by the receiver prior to recording.