The first item would probably be, one who knows by heart, the most Qur?an, and so on?
The most preferred verdict is that most knowledgeable will lead the Salat.
Nabi (Sallallaahu Alayhi Wasallam) said, ‘The most well versed in recitation
of the Qur’aan is Ubayy ibn Ka’ab (Radhiallaahu Anhu)’ but despite that Nabi
(Sallallaahu Alayhi Wasallam) appointed Abu Bakr (Radhiallaahu Anhu) who was
the most knowledgeable to lead the Salaat. (Tirmidhi pg.55). If there is no
knowledgeable person, then the most wellversed in recitation, then the most
pious, then the eldest, then the best of them in character.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai