I knew instantly which school was right for my daughters the moment I walked in the front door. I have actually really surprised myself with my choice - I am far more liberal than I thought I was!!!!! Both husband and I went to Cambridge and I thought I was going to be all over the academic side of things. Something just didn't click with me and the more academic schools. You can look at the inspection reports, reviews, results and leavers destinations until the cows come home but ultimately it has to just feel right.
In reality I love that my kids are being taught to appreciate the other things in life - dance, drama, music, sport, building dens and climbing trees. The school she goes to is most definitely not a hot house but she is being stretched academically - far more than I ever thought - and is doing extremely well. More importantly she LOVES school. Her younger sister has only just started and I am just as pleased with her experiences.
I see friends with children at another school on my list and whilst they are doing unbelievably well, they just seem a bit stressed out about school. Happy, but just lacking in fun.
I can't move at present but if I could I would probably move to Beaconsfield. Choice of excellent preps - in particular Godstowe (if you are thinking of "top flight", usually boarding at 11) and Maltman's Green. There are two excellent all through schools in St Mary's in Gerard's Cross and Pipers Corner. At 11 you then have the choice of Beaconsfield High, the two all through schools and for the super intelligent, Wycombe Abbey. Definitely worth a look if you can consider moving there - great train into London and a lovely old town.
My best advice is go for the school that best fits your family ethos right now. A lot can change in the seven years they spend at prep and you have no idea what sort of school they would need at 11. I agree about wanting to be in an area which will be future proof but we tried that and ended up being stranded at the first hurdle when my daughter didn't get any of our state school choices even though they were our four closest schools!!!!!
In order to answer your question about the "best" secondaries then that would be St Albans High School and Habs Girls in your current area but that is purely based on academic results. Wycombe Abbey is the school that frequently tops the academic charts and admits a handful of day girls.
The three girls grammars in Bucks - Aylesbury High, Dr Challoners High and Beaconsfield High get results on a par and usually better than the other day schools in the area. But then again they are selective!!!!!!