I love french doors or the folding exterior doors that let you open a whole wall but I have 50's ranch and I went with sliding doors because I think french doors don't suit my house. As for the space they take if you have a large deck off of them i don't think it is an issue.

If there is room, consider enlarging the outdoor space to accommodate the french doors.

French doors are more weather tight offer better security are easier to deal with but cost more yes you have to keep the swing area clear and I really suggest having a way to secure the door when it's open.

If you can afford French doors and they're suited architecuturally to your home, they're a much more beautiful option