I'm sorry, what I tried to say was that I want 1 cart dedicated per 1 flavor.
I just figured there is at least 100 flavors to try out there
Now that does make sense. However, most vendors of juice also sell carts, so you just could order a few with every load of liquid.
Having said that, I prefer the medium-flat ones. With the round ones, occasionally I accidentally bite too hard onto my PV, and the top pops off, and I get liquid into my mouth. Not nice.
There are also very flat ones out there, the inner shape is D-shaped. I just could not get one to vape as well as the medium-flat ones, although I guess they are not that bad; just not "my" carts.
BTW, you don't necessarily need one cart for one flavour; not only is it easy to wash out the card and replace the filling, many flavours blend together quite well, so changing carts between them is not that much of a problem.
Because, you know, you have to store and clearly label those 100 carts, too. And that can be quite a logistical problem ...