Good luck in your decisions! Worth really looking at catchment / what is usually offered in terms of usual distance and transport. Partly will depend where you live in Maidenhead.
For example - William Borlase has parts of Maidenhead as an OOC catchment - and is a lovely school! They also run a bus from Maidenhead Bridge.
Our DD goes to Becky High - and girls from Maidenhead have also got into there - I think their open evening is coming up - would encourage you to take a look. Our DD loves it - just started in Y7.
Newlands I also loved - and if you are in catchment / likely to get this as your non-grammar option you are, in my opinion, lucky - as its a great non-grammar choice. The able girls do really well there - and I thought it had a lovely feel to it.
Burnham Grammar is our local catchment grammar - and is also a really good school - we just didn't think it was so well suited to our DD as its not so strong in Music, Drama etc - which BHS is.
As other have said - look at them all - consider transport carefully as your DD has to make the journey day in and day out for many years! We wanted our DD to be able to get to and from without either of us having to get into a car - as we both work and also have a younger DD to consider. So a school bus she could walk to was essential (if she couldn't actual walk to the school itself).
Good luck - its a stressful time