Which magazine is better?

My 9 year old has subscriptions to both, plus highlights and loves them all. She really got into magazines when she broke her arm last summer and had a huge upper arm cast and sling and couldnt hold a book or turn pages well and we got a ton of magazines from the library.
I'd say Ag is a little younger with crafts and such and Discovery a little older with stuff on clothes and friends and a bit on crushes. But both are age appropriate and she reads and rereads them then cuts stuff out and even though they are pricey- really worth it IMO. The 2 libraries we frequent have subscriptions to both so maybe that can help you make up your mind.
Maybe she likes discovery girls better - its hard to say - i did ask her once and she couldnt make up her mind - she goes to half price books and gets back issues of Discoverey girls that are from before she was born (ie 2002) - i laugh and say- just dont take the "new fashion advice" from that issue.