Well this is a great question, but it always comes to the word better. What is best for you is not best for others.
Here we go with this. Ground glass is high end, clean (when done right), works great and harder to make. So for people that like the finer things in life, this is the best joint.
Sliders are easier to make, more affordable, work great and are old school. Nothing wrong with old school baby! The joints will not get stuck like ground glass can if you let it get too dirty or bang it.
So there is the info for you to know what is best for you