I've reviewed a couple of brands, and the difference between them is minimal. Oftentimes, it will come down to which brand your vendor can get at the best price, unless you're looking for strength in one particular feature. If you're looking to compare multiple systems feature-by-feature, first prioritize your goals. Image quality, storage capacity, ease of use, network accessibility, and archiving options are typical key considerations.
I do not discuss the specifics of our equipment in public, but if you would like info on another DVR brand for comparison purposes, PM me and I can give you some additional information.