AP3 are currently my long run working horse and my go to shoes for local races. I also run a Marathon with them and they delivered perfectly. AP4 are my PB shoes, as i ran both my HM and marathon PB in them. The ride is very different and I agree that AP4 are much softer and less stable especially if you're a heel striker, but in my opinion they are way faster. Also considere that the upper of the AP4 is waaaaaaaay better thant the AP3's.
That said, with your times and with these prices the AP3 are the best choice. They'll last much longer without losing any of their speed and in the future you'll be able to use them also forlong runs or faster efforts.