Why not both? It would be a little more complicated, but use two turnouts at each end. The first would go to a reverse loop, with as wide a radius as you can manage. The second would come off the inside of one leg of the loop, probably attached to the first one, and feed a slightly smaller radius helix inside the loop. Continuous running on the visible level, and storage underneath.
If you didn't need access to the storage from both ends, simplify the other end to just the reverse loop.