FN, HK the XDM in this order. They're all 3 excellent firearms but the FN Herstals are some of my favorite to shoot. The HK is up there too while I don't own the XDM I know they sell great due to their price points.

I suggest handling all 3 at a ffl or renting them at a range and selecting the one you like best

The FN for sure.

All three are feature similar. I have only handled and shot the HKVP9 and FN509. The HK fit my hand much better and the point had a more natural feel. I recommend going to a local shop and handling them first hand as opinions will vary greatly and you want what feels best to you when all is said and done. I am certain one will stand out to you. Cheers!