I have a 16gb (Err 11gb after ios8) ipad mini. There is no reason I can't use all 5 storage apps but just wondering what is the best use for each? I was thinking dropbox for just swapping small stuff or once in a while videos since I only have 4gb there. Onedrive I have 28gb and am going to use as an auto photo backup. Box, 10gb there, maybe my PDF/book station, google drive ?? icloud drive ?? Which ones have most compatibility with transferring files like pdfs or movies to your device?