4 iron: 714 AP1 vs 712U

I need to fill a gap in my bag.  My longest iron is a 5 iron in my 714 AP1 irons.  Which would be more forgiving.....a 714 AP1 4 iron or a 24 712U?

Thanks!

The AP1 is more forgiving. The 712U is meant to blend more with the MBs and CBs.