Some comments:
I haven't really seen any ads in DuoLingo apart from their own. I guess my ad-blocking efforts are paying off.
Regarding Pimsleur: I hadn't heard about them, are they only for learning the basics? I'm at A2 french now and aiming for B1. Is Pimsleur suitable for that stage of learning?
Pimsleur is great to improve your pronunciation and learn until B1. From there on I would recommend using Memrise and ClozeMaster. Memrise has a great collection of community based courses that will push up to C1
Babel is really good for grammar and explains well in bite sizes, but it's a little pricy. It could also do with some more repetition imo, however I would recommend it.
Regarding Pimsleur: I hadn't heard about them, are they only for learning the basics? I'm at A2 french now and aiming for B1. Is Pimsleur suitable for that stage of learning?