I subscribed to both AM and FP for years until a few years back when I realised that AM new subscribers were being given deals that loyal long time subscribers were not getting on renewal. I wrote and voiced my dissatisfaction and said I wouldn't renew again next time if they repeated this policy. They repeated it so I didn't renew and haven't glanced at a copy since. Maybe that coincided with the change in editor, I can't remember, but I suppose that policy wasn't an editor's remit.
I like FP and couldn't tell you for how many years I have been a subscriber. The quality of the magazine IMHO is superb. I admit I don't read every article - for instance I might not read an article about historical Japanese or Russian aircraft - but that is because of my personal aviation interests rather than poor articles. Everyone has their niche interests so it's difficult to cater for all tastes.
I do agree with John Eacott though - as a retired helicopter pilot I'd like to see more articles on rotary aviation....but again it's a niche interest and early helicopters, or even relatively modern ones, cannot compete with the beauty of a Spitfire, Lancaster, Canberra, Sabre, Hunter, Gnat, Lightning and their like.