Rupert Giles

At the time of the show there was only two slayers and it was Buffy and Faith and of course we all know this When buffy dies in the gift Faith was busy working with Angel to get back to her normal self it's pretty obvious that Giles was training them three girls to be the next Slayer and we saw them three girls in season 7 but Giles did not choose which one to be the Slayer yet he did not know that Buffy had come back to life in season 6 as we all saw Giles lift Sunnydale before buffy even come back everyone had to tell Giles to come back even when he came back he didn't want to stay and there's your answer he was training them girls as we all know Buffy and Faith only know how to do one thing and that is be slayers no one can ever replace them Faith is better in the city Buffy is better in Sunnydale if they ever build back Sunnydale and we know someone will especially how evil Sunnydale has always been you know it will come back Buffy will be ready as always