well i hope i am not giving a biased answer since i am an ex student of Doha college but i would say doha college is the best english speaking school in doha. it has preschool all the way through to grade 12 (or yr 13 in the british system). i am sure u will find it extremly hard to get in due to its huge waiting list.
there is also:
QIS (Qatar international school)
Aljazeera Academy
Doha Academy
Cambridge school
ASD (American School of Doha) (also a very good school, amazing facilities)
There is also an american academy i think (i forgot its name but it is close to Abu Hamour)
Park House English School
Qatar academy
There is also some new ones im not very sure about, like the Scientific school or the Newton school. I am not sure about their exact names!
I hope this helps.