Expanding the IPCams - new NVR or 2nd NVR?

Hello all,
I've got the following setup at home:
NVR: DS-7604NI-K1(B)
CAM1: DS-2CD2385G1-I
CAM2: DS-2CD2065G1-I
CAM3: DS-2CD2143G0-I

Now, there is a need to install another 6 cams. So I am now scratching my head and thinking, whether I should buy a 2nd NVR, smth like DS-7608NI-K2/8P PoE for another 8 channels.

Or, alternatively, sell the existing NVR and buy a single unit for all cameras: DS-7616NI-K2/16P PoE, for 16 channels.

Currently, I think...

Expanding the IPCams - new NVR or 2nd NVR?