I would say Clifton High lovely for pastoral care, very supportive of additional needs, and academic children also supported. Can attend from 3-18. Quite small school, so although normal sports apply, I wouldn't say they excel in the area sports wise (although often individually children compete at high levels, just tends to be outside of school).
BGS very academic (age 4-18), larger, but children I know there seem very happy.
QEH boys only until 6th form when girls are also now admitted, have heard good things from parents, and they've achieved good results recently.
Clifton College, amazing grounds, boarding, sports facilities great, music facilities great, a 'public' school, so quite old fashioned, but I don't know any children there.
In Bath, I have friends who have children at KES (very academic, probably even more so than BGS), Kingswood and Prior Park. All very happy. Sporty children very well supported, especially for rugby!
Millfield - incredible for sports, I know of a GB level athlete who actually studied elsewhere but came to Millfield every morning and evening for training. Less academic (although am sure more academically able pupils would be well supported).
There are lots of choices, and rarely a bad choice, but the schools do have different feels, and I think if possible, visiting will help narrow things down.
There are also plenty of other possibilities throughout the Southwest, if you want to be near the Cornish coast, Bristol and Bath (and Dorset) are still quite a drive...