Are they family names? I once went out with a Ralph who HATED it. It means being sick to a lot of people, and readers of Judy Blume will certainly have associations..... The only Wilf I know is a dog but actually I do like it as a name.
I'm pg atm and he'll be called Raphael nn Rafe or Rafa or whatever sticks so I clearly quite like those variations. DD for example is called SquiggsyBob which has very little to do with her given name.
I don't like Wilfred at all and really don't like Wilf. Can't really see it on a teen or someone 20s/30s.
I'm guessing as you have Ralph or Rafe then you are going for the old pronounciation of Ralph (as in Finnes) If you are with Ralph people wont generally pronounce it as that (they will pronounce it sounding the L Ral-ff) Either way Rafe looks better and a bit funkier somehow.
Ralph (Guessing Ray-ff) would get mispronounced with Rafe no problem. It is alright not setting me alight. But it would work througout your DS life which is always good Wilfred - no Casper - is okay Ruben - is again alright, looks better with an e (Reuben) I like nn Rue