Having quilted more than my fair share of GFG - and around each and every hexagon - which is how they should be done ;-).....I would highly recommend the Quilters Dream Cotton in the Select weight - the light weight. Your needle does slide thru like soft butter and when you think about all the seams you also have to quilt thru, the lighter weight cotton batting will be nice.
I had always used the Warm & Natural was very satisfied w/ it - til I used the Dream Cotton. It's like you don't realize how bad the ride in your old car is until you ride in a brand new car......
There will be times that I use the W&N, but I'm pretty much a Dream Cotton gal now!!