I cannot really recommend a certain Easter fire - the best ones are the private ones anyway. So if you have any German friends who are having a fire in their backyard, or friends of friends, that would probably be the best choice.
There's some nice ones around the Elbe, been to one in the "Altes Land" a few times, but that was many years ago, so don't know how it is now.
Generally I find the big ones way too overcrowded, smaller ones in the boroughs are nicer, but then again, it all depends with whom you go there imo. It's nice to go with a few friends, if you go only with your partner, it can turn out to be quite boring, can also turn out to be quite romantic...
I'm going to ask around a bit and will post ideas if I hear something interesting