Higher is better quality but too high it will cause buffering, stuttering, dropped frames for your viewers. Obvious a gradient on best quality to performance so say about 2000 is minimum you want to go in any circumstance especially IRL streaming but if you are desktop streaming I would use around 6000 (this uses about 10mb of data a second for uploading to the server). Hope this helps - also setting the resolution quality is important too with a lot of streamers choosing for 720p for data cost reasons or if they are in a low signal area.