I have used two or three different versions of 105 (and currently own a bike that has the 2018 version, 5800), and three different versions of Sora, over the past ~20 years. In fairness, I have not tried the most current edition of Sora...but none of the Sora components I have used came close to the precision and palapable quality fit&finish, of any of the 105 components, especially the most current 105 stuff.

Get 105.