Other than Bach's cantatas, this is probably my favorite body of work for the classical singer. The other exemplars are Schumann, Brahms, Wolf, and Mahler, but Schubert still reigns supreme in the realm of the Lied.
I've listened to probably nearly all of Schubert's output by now, and have sung, oh, perhaps half of them.
Overall, I find these rankings apt and mostly accurate. Really the best is left for last; Schubert's 3 monumental song cycles are all put in the "transcendent" category at the very end, but the songs in them (24 for Winterreise alone) are left unevaluated on an individual basis. This was probably wise.