The ASUS ROG only has a GTX 970 Here is a comparison to the GTX 1070, the 1070 is MUCH more powerfull, it also doesn't come with an SSD which makes things MUCH faster.

The Cyberpower PC is a decent deal although with prebuilds such as that to save cost they get the cheapest possible parts to ensure they can make money from the sale, and because they don't list specifically the parts you are getting with the build you may get some really average/poor parts included. (hopefully not the PSU)

Building your own PC is always the best bet to ensure quality parts, the building process is not difficult at all and can be achieved just by reading instructions that come with the parts purchased and from watching a couple of YouTube videos.

Also asking here with any Queries is always a good bet too.

I recently built my first PC, and it took me about ~3-4 hours, but most of it was just watching videos, but building a PC is the way to go

Your parts list is a much better PC! (Not sure about the red RAM tho and for few dollars more you should go for a Gold PSU)