Tiled2Unity is a great middleware tool that gets the job of taking maps from Tiled to Unity. Despite Tiled and Unity having very different approaches for building up worlds in 2D games, Tiled2Unity makes it seem effortless to port maps over (after you read Seanba's tutorials!).  Perhaps Unity's new Tilemap asset introduced in 2017.2 will mature to the point it can compete with Tiled, but until then, Tiled + Tiled2Unity is the fastest, least frustrating way I've found to author a 2D tilemap in Unity.