Hejira is a distinct masterpiece, no doubt.
I'm not a deadhead and so don't know your second choice.
My Prima / Smith enjoyment is random, but deep. Glad to see some appreciation of mid-century vocal music here..
For some Keely on her own, check out the album (not hard to find on vinyl) Politely, arranged by the great Billy May (mentioned by Smith in this version of the Bunny Berigan classic). May (who could be over the top) knew how to restrain his orchestra in order to serve the vocalist (which is why Sinatra used him on 3 of his major later works). Note the little passages where Smith is briefly a capella.