Should I use VBR or CBR encoding for my OBS CQP recordings?

I know it has been almost a year but hopefully this helps.

YouTube does it's own render on all videos you upload, so it would be best to use whatever they reccomend. I have noticed that the big quality difference comes from resolution rather than bit rate. If you upload a video at 1080p 60fps and use a 50mbs bit rate it will look blocky but if you just up the resolution to 4k 60fps it will look way better, even at the same 50mbs. 

Also, 2-pass VBR is great for your own archives, but again YouTube will just render it again in it's own encoder so you are just burning time using it for YouTube. Personally I always try to render whatever I do at 4k with a bit rate of 60mbs. After that the rate of return is almost not noticable on YouTube. 

As for OBS, if you are using CQP to record footage then keep in mind that the smaller the number the better the quality. So 0 would be highest possible quality and 60 would be the worst quality ever. 14 is near lossless, after that it is more details for any footage you want to zoom in on and not have it blocky. I use 14, and always turn off Max Quality settings. Again, that is almost placebo effect, it is just for footage you will be zooming in on. If you are going to be doing insane amounts of editing then go for it, but if you are like me and just recording game footage then just use the quality setting, CQP at 14 or 18. No look ahead or phyco tuning either, same thing.