Tunbridge Wells Girls Grammar School (TWGGS) is not "super-selective" so takes any girl who passes the 11+ regardless of score, but you have to live within around a mile or closer to the school to be relatively likely to get a place. They also have a limited number of Governor places which are purely on score, but in recent years these are all from the Kent selective area - if there's a tie on score then the closest girl gets the place.
Tunbridge Wells Grammars School for Boys (TWGSB) is also not a super-selective and takes from a wide area including as far north as Sevenoaks and sometimes, if spaces, boys in East Sussex (e.g. from Groombridge or Frant).
The Skinners' School (not to be confused with Skinners' Kent Academy) is a super-selective and takes the highest scoring boys who apply. They come from as far afield as Bromley and Hastings.
The other grammars in the area are Tonbridge Grammars (girls), Judd (boys) both super-selective but with a inner and outer designated area. Weald of Kent is also in Tonbridge and is girls but not super-selective.
Are some better than others? Depends on what you want from a school. Certainly the super-selective get the best results, but you'd expect that bearing in mind they take the pick of the students. TWGGS always does very well and has a good reputation. I've a DS at Skinners' and he's enjoyed himself immensely and did well at GCSE. None of the schools are bad.
Best place to move to would be central Tunbridge Wells within a mile radius of TWGGS.
Of course if your children don't pass the 11+ then unless you get religion in year 3 your other options aren't so brilliant. Having said that, Skinners' Kent Academy is rapidly improving and has had a shed load of money thrown at it recently.