Maynard is a fine school. It is all-girls of course, and you need to make your own mind up about that.
In all fairness I won't comment on Exeter School. The Leather lady has coloured my judgement.
Queens and Wellington are both good schools.
Queens is very strong in dyslexia and learning support. The syllabus is GCSE; Latin was dropped a few years ago. The headmaster is an affable northerner. Much money has been spent on facilities for art and drama. It is a Methodist foundation, and still has a slightly non-conformist feel.
Wellington has adopted iGCSE for certain subjects. Latin is offered, and also Ancient Greek. The headmaster is an approachable Oxford man. Much money has been spent on facilities for music and sport. It has a direct-grant school background, and still has a slightly grammar-school feel.
...but don't rely on me