I have no experience with Staub and only just recently got my first piece of Le Creuset so I have very limited knowledge on this. That being said...I love my Le Creuset and I have also heard great things about Staub.
As for the ability to maintain low heat, since they are both cast iron they will both work very well at doing this. The heavier it is the better it will be (more mass) so if you can weigh each piece this should give you your answer as to which would do a better job. I have a feeling though that one might do an excellent job while the other might do a hair better than excellent. Basically both will be fantastic at holding and maintaining low temps.
Food should not really stick to either of them since they both have a ceramic coating. This will also enable them both to clean up very easily.
I have no idea about the durability of the ceramic coatings though. The literature that came with my Le Creuset french oven makes it seem like you have to be careful not to chip the coating, but I am guessing it is quite a bit hardier then they lead you to believe. I have no idea about Staub, but I would guess it is close to the same.
The dimples are a good idea in my opinion. The help the condensation fall in a more even pattern, but I would guess that is just an added bonus and not a necessary feature.
Again I have very limited knowledge in this, but I would think both brands would be very good and if you are not buying based on the name then get the less expensive one as I bet they are both pretty comparable.