Which is better for a ball tool?  I am considering investing in a metal one if it works better than a plastic one, which I have.  What are the pros and cons?

I have both, my plastic one has a seam and sometimes tore at my gumpaste when I was rolling my petals thin, so I bought a metal one. I think plastic would be fine as long as it doesn't have a seam.

Even my seamless plastic one seems to grab at the gumpaste just a tiny bit, I would definitely invest in the metal one.

Just got one!  I'm very excited!

I have both and I also use the Celstick.but  pretty much use my metal one.  I have the metal one by Collete Peters.  I love how it fits in my hand -  have had it for years.

All ball tools will stick at one time or another depending on the gum paste and or fondant you're using as well as humidity. 

Have tried plastic, acrylic and stainless steel. Love the stainless steel won't use the plastic or acrylic again.