Without wanting to sound too morbid I sure as hell know which one I would want If I had an accident with a kid in the back, the one with the rear emergency exits.
Very good point actually. Que the "rear doors never open in a collision" comments, I'd much rather have the chance no matter jow small.
Except on a 5 door you will more than likely have the childlock on so they won't randomly open the door
Pro's and cons, I find with a 3 door you tend to literally climb in to strap them in, on a 5door your at a side angle which is somewhat more awkward. But as anyone knows with kids, the sideways approach is easier when the kids are kicking off with their feet and booting you in the face because they don't want to go to location "A" or leave location "A". I'm sure anyone with a 3door has experience being booted in the face.
For me I prefer the 5 door, more easier to get things like prams in and out encase the boot is full (ie doing a big shop) and you need to chuck it on or in the back. Shorter doors, as they age I find they can get in and out quicker, the child can see more, especially when you get stuck in traffic with a lorry full of pigs and all your daughter can do is shout "pepper pig". I'd go 5 door personally for the pro's stated.