I will choose the FLiP Try-It Kit every time! The high quality of the hardware and these excellent educational resources are the reasons that the decision is easy!
Note: I am already playing with the FLiP and loving it. I'm so glad to see this kit for teaching and learning. I've been enjoying BlocklyProp since the release of the S3 robot! This is great stuff for students, educators, and hobbyists and Parallax's support is second to none!