There is a distinction to be made between NVR and DVR systems. NVR systems work over a network whereas DVR systems must be wired to their analog cameras.
NVRs are simpler to set up and are more or less easier to work with because the cameras work over a network (either wired or not). This improves compatibility and also requires less installation and wiring than a DVR system.
However, a DVR system will work well if you are looking for a system that will also handle your older surveillance cameras.