Two are just so different imo.
Exploding while her mouth wrapped around you cock is something so psychically intense + its kinda naughty since its seen as to find a women who is a good at swallow is hard to find.
On the other hand facials are different. If you look at it simply at the bottom of the line psychically there is not a tiny bit difference between jerking on her face and jerking in a sink. In both situation your hand does the job only in one liquid hits a face rather than sink
So actually pleasure of cumming on her face is totally a dominating issue. The Feel of unloading your sperms on her face. Something so private, naughty. Something post of the porn films put in your head; naughty girls like facials. Something so dominating.
Even position wise. For the best face cum you need to stand higher and she has to be on the low ground. See again a domination issue (even if you don't think its not like that actually it is. very basic sub subconscious thingy)
again... imo
