I have often felt that a standing system among the factions would be a lot of fun. But…the only way I can think of to raise reputation/standing would be to perform quests or fetch quests for that faction. And Funcom had previously said that they are not planning to implement them. So while a fine idea, I cant see how it could work.
Although I have previously suggested that the factions should raid each others camps. Seeing a hanful of Black Hand raiding Dogs of the Desert, some Bandits raiding Sepermeru, or so on would be cool to behold. Here is where I first discussed it waaay it if you are interested. 
https://forums.funcom.com/t/the-sugestions-of-croms-faithful/48825