I have used a lot of diff AGM batteries and really am not seeing much difference in life between them all. I have not used a northstar in a long time, very hard to get. Optima, Deka, everstart from walmart, house brand at o'reilys, etc. I just am not seeing a difference in the life between them all. The Ford battery seems just as good as the rest and I wouldn't hesitate to go that route. 4 years doesn't seem bad for how much it is used. If you really cared, I bet you could get another year or two if you put the battery on an AGM specific battery charger once a month. I tested this on one battery and I felt like it really did make a difference. I am not dedicated to do this all the time on all my batteries but I do try to charge them maybe once a quarter.
I don't know the details on the ford charging system but typically car's charging systems are not setup for AGM batteries so they never get a full charge.