IMHO a lot depends on what you're trying to focus on scrapping. Maya's "Near & Dear" is an amazing collection if you want resources to create a family album. Tanya's "Play On Elements" has some wonderful unique sets for "special pages", and if I had little ones I'd snatch Anna's "Baby Daze" up in a heartbeat!
For all around basic design however I find that I reach for one or the other of Gina's CDs ("Digitally Sparked" & "Spring/Summer Collection") over and over again. Gina's kits are marvelous when it comes to mixing and matching and give you a lot of bang for your buck. But don't ask me to choose between either one of them...it's impossible!
With that said, there are so many other wonderful CDs out there that I've got on my "to buy" list....Julie Mead's "Girly to Grungy"....Holly's "Digi Chick" stuff.....oh heck....just about ALL of them appeal to me! (Maybe I'll talk to Santa and see if Jules is the ONLY one he comes early to!)