I've had both, and in the house we're designing for our retirement we're planning to have . . . neither! We're going to have a typical spot in the dining room where a slider /French doors would typically lead out to the patio; however, we're going with a bank of windows and one single "real door" with windows on the top half. It's more secure than either sliders or French doors, and the windows are more practical for air circulation.
One thing no one's mentioned: Sliders and French doors are both rather difficult to "dress" with curtains. I think I'd definitely like the blinds between the glass, but I'd still want curtains to soften the hard lines too.
One thing no one's mentioned: Sliders and French doors are both rather difficult to "dress" with curtains. I think I'd definitely like the blinds between the glass, but I'd still want curtains to soften the hard lines too.