The problem is that there is no "standard everyday speaker" really. Just among those 3 brands ya listed there are 10 different models of 6x9, all with different performance characteristics and TS specs. So to give a general answer is really, really broad and of very little real help.
As a general answer, I'd say most 6x9's do benefit from some kind of enclosure. And all speakers need their front and rear waves separated to avoid cancellation so a "baffle" is always required, even if there is no enclosure.