I don't think it's as clear cut as I first tought - Disneyland Park is the obvious choice BUT if it's a really busy day like a Saturday then the Studios park would be much easier to navigate and you'd feel far less hassled. There are a great array of attractions like Moteurs Action, Tram Tour Ride, Armageddon, Rock 'n' Roller Coaster, Animagique, Cinemagique, the amazingtheming of Studio 1 etc...
I'd say there is no chance of doing Disneyland Park in 1 day if it's busy and a different option may be to go with a mind to return. In that case Studios could be done comfortably in a day, including a meal, and then you could pop along to the main park as a taster for your return visit. Maybe check out a ride or two, take in the atmosphere and watch a parade.
Trying to do Disneyland Park in one day if it's busy may leave you fustrated and having missed out, and also having seen none of the Studios which offers some great attractions.
That's just an alternative option anyway.
However, if you do not plan on returning ignore all the abve and cram as much as you can of the main park in your one day! Best bet would be to post what your favourite types of attractions are, for both parties going, and then seek advice from us lot - nutters that we are, the parks are in our blood and we love nothing more than hearing what people like and matching the attractions to people's needs!
Whatever you decide to do, have a great time in Disneyland Resort Paris and welcome to DIS
