I've done Old First and CW with an infant and now a toddler.

IF the cabin is full there is a chance that one parent can sleep slightly more comfortably in F due to the slightly wider seat than in CW.

I understand there is a bassinet position in New First (4A?) but have never used it.

Therefore I'd go for First, and hope that the cabin isn't full (ours was, and they offered us a CW seat in a two thirds empty cabin for our daughter to sleep in!).