Best Neal Morse album to start off with?
Depends on what you like... and also, be forewarned, his lyrics since leaving Spock's Beard/Transatlantic are more outwardly and extrovertly Christian in message and meaning. They can be a bit praise-y and worship-y at times, but if you take them for what they are and are not easily offended by religious lyrics, then you are probably ready for ANY of his five albums.
I would probably suggest
?. If you're a fan of Transatlantic and Spock's Beard, I'd say this album is most like his previous works with those bands, and it features an array of musical guests that are surely to delight (Alan Morse, Jordan Rudess, Roine Stolt, Steve Hackett, and as usual Mike and Randy on drums and bass). It's a single piece divided into 12 tracks (sound familiar?), and runs about 56 minutes with varying themes, which aren't beaten into the ground like they are in
Testimony. And don't worry if you are a collector of varying editions, there's only one edition of this album.
After that, I'd suggest getting
One (Special Edition). Definitely one of my favorite Neal Morse albums of all time, and the special edition has some greats songs that were cut, as well as some sweet covers!
-Marc.