My choice of listening to Morse-Era and Post-Morse SB waxes and wanes every now and then, but lately, I've been VERY into Morse's work, with SB, with TA, and his (prog) solo stuff.
Obviously, I think a lot of SB fans will look to the Morse-Era as the better stuff, but after awhile, you can notice he develops a LOT of Morse-isms in sound, style, technique, and composition - his use of spanish-style guitar and sounds, his thematic reprises, grandiose epic endings... after awhile, you even notice melodies he reuses/rehashes/remakes. There are bits in his first two solo albums (while with The Beard) that he uses later on in his prog-solo albums...
Anyways, I do agree with Kev - the first 6 SB albums are pretty essential. At first they may sound all the same, but you get to find what's special about each album, and appreciate each album for it!
It's hard to pick a favorite (of those six)... I've been loving The Kindness of Strangers lately, but I think Snow will always be top dog. It's so unlike the other five, for being a concept album (which I am a sucker for), but the other five albums are pretty damn good.
Of the Post-Morse era, Octane is my definite favorite, but it has to be the Special Edition with the bonus disc (which is a shame - most of those bonus songs are really good!). Feel Euphoria and the s/t Spock's Beard are pretty good too, and I'm looking forward to SBX! Still gotta pre-order it though...
-Marc.