TimeCapsule. Less cable clutter, better drive performance, just a small premium over a AE plus NAS quality drive (you can go cheap on the AE external drive and enclosure but that more like comparing apples and oranges). You can always add an external drive.
I just went through the decision and chose the TC.
If you want, you can swap TC drives. I extended the life of my timecapsule by replacing the drive. Not that difficult, many mod descriptions on line and in YouTube. It is much easier to swap drives in the newer models, many here throw 4TB drives in.