I am having this problem with my printer. It doesn't print smooth circular objects. The objects are typically "ribbed" or ridged... never smooth. I am not sure how to fix this.
I have tried fixing it in Meshmixer, I've tried Sli3r (I normally use Cura 2.7). I've tried turning down acceleration as low as it will go (500 in my printer's case), tried slowing down the actual print and travel speeds. Short of just replacing the dang thing (not an option at all), I have no idea what to do... I'm at a total loss for words here.
My printer is a TronXY P802MA. Auto Level, runs Marlin firmware. I use Octoprint as my print server. The picture shows the odd texture. It's at the bottom of this particular model. For some reason, within the pictured model, the problem isn't reproduced in the partial spheres.
Did you try to use different infill? Denser or less dense?
You can also try to reduce overlapping infil with outlines.
Try to set 2 or 3 outer perimeters / outlines.