So you're looking for a shoe, well you better forget about looks for now, as there is nothing trendy about most parkour shoes.
First thing you do when you pick up the shoe is feel the weight, they should be very light. My personal favourite, the kalenji success, weighs only 290 grams and these are perfect. However you could settle with about 1000 grams. When you have the one you want move on to the next step.
Next thing you look at is the sole; it should not be too many layers of rubber because these will fall apart a lot easier. Try to find one with rubber coming over the toe of the shoe as this will be a way for your toes to grip and act as a small shock absorbent. For the overall grip just try to rub them across the floor and see how much they catch against the floor.
The final step (in the way of parkour) is the size. You want them slightly loose as if they are too loose most of the grip that you just found will be lost as their will be far too much space between them. However if you have them too tight you may find that the grip might be a lot better but your feet will be aching after just a light session of parkour. Try to find something in between
The last step is merely cosmetic, if you're worried about this try to cut down on some of the above if you are worried about the cosmetic issues.
Thanks for reading, if there are any questions then don't be afraid to ask.