Is deciding to cover your face/head just a matter of personal preference, or is there some level of liberal/conservative groups within Islam that one would get guidance from on that issue?
All scholars agree that hijab (covering the hair) is required and proof of that is this verse:
“And tell the believing women to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts) and not to show off their adornment except only that which is apparent (like both eyes for necessity to see the way, or outer palms of hands or one eye or dress like veil, gloves, headcover, apron), and to draw their veils all over Juyubihinna (i.e. the their bodies, faces, necks and bosoms) and not to reveal their adornment except to their husbands, or their fathers, or their husband’s fathers, or their sons, or their husband’s sons, or their brothers or their brother’s sons, or their sister’s sons, or their (Muslim) women (i.e. their sisters in Islam), or the (female) slaves whom their right hands possess, or old male servants who lack vigour, or small children who have no sense of feminine sex. And let them not stamp their feet so as to reveal what they hide of their adornment. And all of you beg Allah to forgive you all, O believers, that you may be successful” [al-Noor 24:31]
Regarding niqaab (covering the face) there is a difference of opinion whether it is required or not. In Islam, if there is a difference of opinion between scholars on a certain issue, then you choose the opinion that you feel is right.