I play on All-Madden because All-Pro is too boring. I don't want to brag or anything but All-Pro offers no challenge at all, losing isn't even a thought on that difficulty. To be honest, All-Madden isn't that hard either. You just need to learn the CPUs tendencies and what plays to call.
No matter the difficulty the AI will still come out in Cover 0 and press Julio Jones with an 80ovr CB. You've just got to outsmart them. The other team just changed their formation? Audible your play too. They changed it back? You change back too.
On All-Madden you'll noticeably get a very poor pass rush. If you send a blitz they'll block enough players to stop it so it's best to just stay in coverage. Stopping the run isn't too bad but you have to come out in the right personnel or you'll get gutted. The CPU is also very dangerous with jukes, no matter the defender I've noticed the CPU has a 100% success rate when using juke moves.
It helps a lot to user a LB, the CPU is very good at finding holes in coverage so you have to take away as much of the field as possible.
Minimizing mistakes is key. The CPU isn't going to drop that 50/50 interception, so you have to keep your players out of those situations. I notice people talk about DB super speed and CBs coming from across the field for picks, and no offense but I believe those people just aren't as skilled as they think they are at the game. You have to know what plays to run and when to run them, you have to be able to recognize coverages and know what plays take advantage of those coverages.
All-Pro is probably a more "sim experience", but depending on your skill level you're probably gonna lose interest in playing games. All-Madden is seeing changes in gameplay and ramping up AI to make it more difficult, so it's definitely a less sim but more challenging experience.
I could probably keep going with this write-up but that wasn't really the point of the thread so I tried to keep it on the short side.