Depends entirely where you are. Lower league teams can be carried by one or two solid players. So can top teams (Man Utd, Rooney/Ronaldo so a few in the media used to say).
But having 11 good players is always a nice thing.
11 good players, preferably 22 as I run that sort of meritocratic system that needs the depth. I'd always spread my budget around if I need a few playes rather than go for one or 2 expensive ones but leave gaps unfilled.