that's a very good question... one that I won't answer because at the end of the day it's personal preference.
I will say that have shot several Hammerli pistols and they were nice and way more accurate than me, but, I have not shot the AP 20
I will say to look at what they are shooting in air pistol matches.
I have two 10 meter pistols, A FWB P34 and a Steyr Lp 10E, my favorite is the FWB because it fits my hand better than the Steyr.
I think the LP 10E is slightly better quality but I shoot the FWB better because of how it feels in my hand and that is where personal preference comes in, in my case if I had to sell one it would be the Steyr.
I like my Steyr LP 10E, but I love my FWB P34
You can have the best of the best but if it does not feel good to you then you will not be shooting your best... If you have any way to try one out before you buy it I would, even if you have to take a road trip to do it.
that's my opinion anyway