I have several of the second style type of Chanel card holders, and they all collect dust. I have a YSl one similar to the first one, with a flap, and THAT is the one I use the most. Way more practical and can hold more things securely.
I have both styles and they are both great, but it really depends on how much you carry. I use my flat card holders (second pic above) way more than my flap style (first pic above) because I usually carry very little (2-3 cards, driver's licence and a few other odd bits) and rarely carry cash or change. I also like that it takes up much less space and fits in even my smallest bags. But if you carry more (lots of cards, change and/or cash) the flap style might be better for you. Another nice style if you carry more is the zip around coin purse, which has 3 interior slots, or the zip around card holder, which is slightly larger and has 4 interior slots. I have the coin purse version and use it for cards. I find that it holds about the same amount as the flap style, but is a bit more compact because of the zip around feature.