Well, Sophie and Sophia have been climbing the charts the past several years. My eight year old daughter knows one of each her age.
I do love the name, too, so you first must decide if you'll be all right with it being your child's name, if it becomes the next Sarah.
Audrey is also getting a little popular, although it's not in the Top 50 like Sophia. It seems to be more popular than Sophie even--although I haven't come across any Audrey's in my area--but if I hear of many Sophia's, I'm going to connect it with a lot of Sophie's nevertheless.
As for my personal taste, I like Sophie better than Audrey. However, I also love Aubrey (with a b).