Ecoradicals: they blame all the shit on overcrowding so basically they banned/controlled re production.
Tecnosaviors: their predicament is: "technology will save us all", they embrace AI worshipping and sell technology to fund research.
Extintionists: they actively seek the extinction of humans in order to restore nature. Their motto is : we are the last one
Tribes: they don't see themselves as a faction, they are small self sufficient groups of people that artificially secluded themselves in closed valley, islands, steep mountain peaks.
Just a bunch of archetypes instantly spotted out of my imagination.
Ciao!