I think this is something lots have wondered about.... high or low... CSGO is much more playable with low sens due to the predictable flow of maps.
Ultimately it takes more skill to be accurate with a faster sens. Slower sens gives you easier accuracy at the loss of movement / manoeuvrability.
Really you need to decide on your gameplay, and be realistic with your skill level. There's some incredibly accurate players using very fast sensitivies.
My highest scores in kovacs aim trainer are with slow sens, but it's not practical in game. Theres always pros and cons, different games weigh up differently.