Mega-Pixel security system. should i get BNC or POE ?

I currently have analog BNC set up. I want to get a new system with Mega-Pixel cameras.

I was able to find analog BNC 8 ch 4MP camera system for $450 w/ 8 cameras (Costco Wholesale).

I found a POE system 8 ch 4MP camera system $600 w/6 cameras. Audio in all.
(Swann 8 Channel 1080p HD IP NVR Security System with 4 3MP Cameras, 2TB Hard Drive,...

Mega-Pixel security system. should i get BNC or POE ?