Hiya
I live in Brighton and have done for nearly 20 yrs, and agree with what Pollyanna says really.
There are some good schools in Bton - state and private. Hwr, the good schools are all over-subscribed, so I would worry that you might not get a place...You cannot apply for a place in a state school until you have an address in Brighton, I believe, as places are allocated on distance-based criteria. In the meantime, your child might be directed to the nearest undersubscribed school, which MAY be a bit sh*te.
Hwr, the places to live in Brighton to be in the catchment for the 'best' schools are Fiveways, Preston Park, Roundhill, Preston Circus, Stanford and Prestonville areas, or their immediate neighbours. I am not sure about Hove though, although Hove Park would be a safe bet.
Have to say that catchments at the best schools have shrunk a lot in recent years, plus, while my dd goes to an Ofsted rated Outstanding School, I feel a bit disappointed by it, so it is hard to judge.
Balfour, Downs and Stanford are the highest rated though...
As for private, Brighton and Hove High School (BHHS) and Brighton College, plus St Mary's Hall all have very good reputations.
When moving though, I would be looking at Senior School catchments too, as there are two ok schools in Brighton and some really rubbish ones. The council have recently amended the criteria for these schools, but once you have an address in mind, I would phone the council if I were you, to find out which Senior School would be the one for that area - it would make a big difference...
hth