Both are excellent - Flyer is aimed more (in my opinion) at people who have to think harder about how much money they have to spend on their flying than Pilot, which assumes more that you just have enough. Having a limited budget, and liking Ian, I am more likely to buy Flyer.
The other two I rate are Light Aviation (formerly Popular Flying) which comes with my LAA membership, and Microlight Flying, ditto BMAA. LF is much better for flight tests and engineering advice, MF is much better for trip reports.
I just wish I could find the blasted time to do them all justice. Hence that the only subscriptions I have are with my association memberships, and I buy Flyer and occasionally Pilot when I think I'll actually have the time to read them that month.
I'm also very much a fan of the US magazine Flying, which has the sort of detailed thoughtful writing I particularly like. I have failed miserably to get them to do an overseas subscription for me - so buy it when I'm in a suitable newsagent outside of the UK.
G