Top left position
Pros:
It's near the gate and is easily accessible. You can allocate it with various paths etc. It's next to a river as well so it has more tranquility? idk. It's also not over-shadowing anything.
Cons:
It's right next to the river so you won't have much space to decorate it (adding bushes, trees, flowers etc.) You definitely will not be able to get a PWP in front of it. Also, the way it's right next to the bridge may entice people not to travel down that small side of the map above the river, as the Cafe will give a "blocking" effect.
Next to the cliff
Pros:
It's a scenic location. It's also fairly accessible.
Cons:
Again, with the previous location you will not be able to accessorize the cafe's exterior. There's probably not enough space for a double path. It WILL over-shadow a big space in your town, so if you have plans to put a path/pwp near the plaza then think again as the bottom of it will probably be over-shadowed by the Cafe.
Top right position
Pros:
It's VERY accessible. There's a lot of room for customization outside of the cafe. There's room for PWPs, Paths, Bushes and even trees! It will add more traffic towards that currently un-popular part of your town. There's no over-shadowing due to it being next to the train tracks. It's quite near to a cliff so you could use this to your advantage and make a scenic area right next to it, idk.
Cons:
Can't really think of any...