GMD are cut wider I believe so you get more use from each size? Someone can correct me if I'm wrong. I personally went with LL because they were cheaper - I bought the premium size for my then 4 month old (who technically would have fit in the infant size still) and just folded it down more. It was a lil more bulky at first but now I'm glad I saved the $. We love our prefolds!
I ordered a dozen of each last year and ending up selling the LL right away. They were so narrow and hard to snappi so I kept the GMDs and have stuck with them since. Love the GMDs.
Re: GMD or LL prefolds?