[Dodecanone]

Alright, so I need to determine the factors that affect delta octahedral for complexes and then apply my list of rules to some compounds and determine which has a higher delta octahedral.
My list includes:
1. Delta octahedral is large for low spin ligands and small for high spin ligands
2. Delta octahedral increases with increasing metal size
3.  Delta octahedral increases with increasing metal oxidation state

Those three have gotten me through most of them.  But then I came upon this one:

W(PPh₃)₆ versus W(PF₃)₆

I cannot find or determine a rule based upon size of ligands.  Is there some rule for that? Or is there another way to qualitatively evaluate which of these would have a higher delta octahedral?  I'm pretty sure that both Tungstens have the same oxidation state. 

Thanks!