before making a build you gotta do a decission:
Do you only want to shoot enemies?
Do you want to go melee as often as possible?
Do you want to be able to go melee? so in case that you are prepared.
For decission 1: (lvl 35)
Go 18 30 without IF, Shield and ps
so only 10 wm and 10 ath.
Than you skill everything on crossbow and you will be a awesome sniper. Your crosshair will be almost closed.
For decission 2: (lvl 35)
Make a 18 27 build with ...
9 wm
9 ath
6 ps
2 if
than try to split up the wpf to:
one handed: 157
crossbow: 135
For decission 3: (lvl 35)
Go 18:27, same build as with decission 2, but:
one handed: 100
crossbow: 177
For sure there are many other kinds of crossbows, I for example played a 18:27 Full plate with lvl 36 and it was crazyly awesome. But full plate without good gloves
but at all nobody can tell you what build you have to take.
If I was you, I would go 15:24 and than just check what I need. Do I need to be a better sniper? Do I need to be faster in melee? doing more dmg and so on. That's the best way to find your build