We live overseas so practical considerations like getting to airport (Gatwick), not emptying out on weekends and not that many exeats are important to us.
Marlborough was probably my least favourite mostly because of facilities, I feel, being more run down than most other schools we looked at and because of some of the scary things I read on Mumsnet about it but does tick many other boxes such as good friends going there, closest to airport and most importantly has the choice of IB which the other two don't.
We liked the feel of Rugby and loved the house which DS got into. Doesn't seem to be equal to Oundle to academically but not sure. The town is dreadful but at least it has a train station. Seems to be stronger on the pastoral side than Oundle.
Oundle is where many people from our country go to. It seems a little cold on the pastoral side to us though. Also cannot tell whether it will end up being too much pressure on the academic side as all I hear is how exhausted the kids are from work. They do have great facilities (although not really in the houses) and their system of voluntaries seems to be brilliant for those needing extra time on a subject.
Any feelings from people who have kids in the schools would be great. Our DS is a friendly and outgoing boy but he is also sensitive and does get homesick (currently boarding in his first year - year 7 - at prep school). He loves sport but not fantastic at it. Academically he is in the middle and does well with a push and positive support. He has the ability but probably not always the drive.