well, the first one is completely different to the others. It is more of a shell, whereas the others are more 'carry case'-like.
Out of the bottom two I prefer the leather, it looks nicer, is smaller, and provides better protection against drops but has a few real flaws:
> By the looks of it the DS just 'sits' in there and will fall out if you open the clip, and possibly even fall out the sides even when it's done up.
> The games look like they'll fall out very easily, i can imagine (after some wear) they'll fall out the slots then slip out the sides.
> It only carries 3 games (though this won't be a problem in a few months time if ya no what i mean
)
So you need to decide when/where you will use it and how easily things may be lost depending where you keep it. If you do go for the leather one I would do as the above poster said and use it in conjunction with the yellow case. This will prevent it's 'nakedness' (if that's what you want to call it) and also provide extra protection for when it falls out of the leather case after you open it upside-down.