I've never used Github Desktop but SourceTree has its own set of glaring problems from interface to functionality. I stick with the command line these days.
SourceTree just became worse and worse with every release, to the point of unbearable. I am using an old version of SourceTree (1.5.2) and it works great.
I hate to be the bearer of bad news but that version of SourceTree is affected by this security vulnerability: