There's a huge backstory to the QKS ofsted. It's worth reading the Westmorland Gazette and the school responses to try to understand it better. The ofsted report itself was pretty good for sixth form, less so for KS3&4. Gets very mixed reviews from parents locally.
Kirbie Kendal was always seen as a 'worse' school that QKS but it has an improving reputation and has increased numbers in year 7 this year. All the staff I've met seem great. They do a lot of high profile drama/musical events in town. The building itself is rather decrepit if that matters to you.
If it's only the Kendal schools you're interested in then it's worth visiting both.
Further out, both QES and Dallam run buses from Kendal. QES has been sitting on an outstanding ofsted for years and is long overdue a visit, but everyone I know who works there or has kids there raves about it. Go to visit, and try to peak behind the scenes - the newer 'public' areas are a bit different to some of the classrooms.
Dallam is also overdue ofsted. Lots of changes (for the better I'm led to believe) since the current headteacher started about three years ago. Quite a few staff seem to send their kids there which seems very positive. Mixed reviews from parents.
In the other direction you have Lakes school near Windermere (ofsted have just visited - report due any day) but more pupils seem to head into Kendal from that side rather than out.
Personally, I'm seriously considering moving out of Kendal to get into catchment for Cartmel Priory School. Excellent pastorally and rapidly improving academic results. No sixth form though so might not work for you.