Electricity Provider

Hallo,
I just moved into a new apartment in Erlangen. Since I haven't officially signed up with an electricity provider yet, I am currently on the local default with ESTW.
I've heard a lot of people talking about Ostrom as a great digital alternative, but I also heard from a friend that the local ESTW Erlangen might actually be cheaper. I'm not sure which option is better, so I would really appreciate it if someone could help me out.