PhD4Me?

I have been offered a PhD position at the school I am currerly doing my masters at. This is good but I am unsure if I should take this option or apply to different programs elsewhere. I did my undergrad at a Big 10 school and am doing my masters at a less well established school in the south. I am concerned if I stay to do a PhD at this school it will be detrimental to my future but am having a hard time passing up an offer where I know who I would be working with and what I would be working on. Any suggestions?