What DVR would you guy recommend me getting? I would be looking for one that at least can support 4 cameras but do need one which has DDNS so i can use it with Hikvision. What would you guys use?
These NVRs support Hikvision's free HiDDNS service, as well as DynDNS and No-IP which are commonly used DDNS offerings. I would suggest a Hikvision NVR if you're planning on using Hikvision cameras for optimal compatibility.
If you're planning on running 4x 4MP cameras, I'd steer clear of the DS-7604NI-E1-4P. It has been our experience that the NVR begins to struggle and can't handle the four cameras reliably if they're running at 4MP, with 12+ frames per second. The 7608 would be the one if that's the case.
I'd go with either a selection of cameras from Hikvision's 3MP or 4MP cameras at the moment - very popular, and very cost effective. https://www.use-ip.co.uk/hikvision/4mp
Hard drive is a little harder to spec as it depends on how long you'd like to retain recordings for. You'd want approximately 2TB of storage space for 14 days. https://www.use-ip.co.uk/western-digital