Concrete for sure. You can do a "stamped concrete" with an added Scoffield color and a sealer if you want a nice pattern in it.
You might want to also look at doing interlocking pavers. They look great and have a massive compression strength. They are typically placed over a solid sand or gravel bed. The other nice thing about going with pavers is you can remove an area to deal with a root or something else, then re-install them. Of course, they are most likely not the best to roller skate on!
