I have been using both for some time, although I only paid for one, which is ChinesePod. Actually, you don't need to shell out 250$ to get your money's worth at CP, I just took the basic package for 124$ a year, which allowed me to download MP3s and lesson PDFs. I personally don't need fancy apps to learn Chinese, I'm old-school. I listen to the MP3 and then sit my ass down and study the lesson at home.
My level was Upper-Intermediate/borderline Advanced, so that's what I studied. All in all I listened to maybe 500 of their lessons over the course of one year, and it was incredibly helpful to my listening comprehension. I think the lesson content is alright, certainly much better than your standard textbook fare.
Popup Chinese offers much less content for the advanced learner, and they lack an upper-intermediate level. I think the difference between the intermediate, where they still speak tons of English, and advanced, Chinese only, is too large.
The stuff they do offer at advanced levels is pretty good though, and the content is more colourful. As of right now, all I do is listen to their advanced stuff online every once in a while and that's it. I can't really comment on their paid advanced content though.
Overall, I would recommend CP over Popup, simply because they seem to have much more material, you simply get more for your money. If Popup manages to put more lessons out and maybe introduce an upper-intermediate level to make the jump to advanced easier, then I'd say they would be slightly better, simply because they are less "stuffy" and more fun to listen to.