Your logfile seems fine, with YouTube videos your videos are first compressed and allowed for playback via avc1.x codec, which is not that great at all for quality retention. After a time your videos will be converted by YouTube to vp9, which offers higher quality playback, though only slightly better than avc1.x
In regards to replay buffer, are you referring to the standard buffer rate control method? If so, your buffer value is fine. If not then do you mean automatic recording to allow for 'last xx seconds' capture? I do not know if that is possible.
The following settings, given you have a rx480, should allow you to have no issue with recording at 1080p60fps, with great quality:
Quality Preset: Quality
Profile: High
Profile Level: 5.2 or 5.1
Rate Control Method: VBR_LAT
Minimum QP=0, Maximum QP=42
Target Bitrate=50000
Peak Bitrate=90000
Leave everything else at default settings, for some more advanced settings, refer to the following link:
https://github.com/Xaymar/obs-studio_amf-encoder-plugin/wiki/Configuration
However, you have a 3570k, which will limit you somewhat in terms of what your GPU can handle with recordings, as it also does some of the workload when recording with your GPU.
If you have fps issues in-game when recording or on playback of your recording, first check that your CPU is not hitting `100% load on all cores, if it is then upload another logfile post recording and we'll see how we can modify it a tad to ease the strain on your CPU (It is the limiting factor for me, I record at 1080p60fps with an i5 2500 non-k and r9 290x, with only BF 4 'hitching' slightly every so often due to CPU limitation. Your CPU is just a bit of an optimized version of my CPU, same for the video card, though it is much improved for recording)
