When discussing progressive metal, it becomes near impossible not to mention Dream Theater. They set the bar of excellence for an entire genre-- they are the definitive band for that entire genre.
Unfortunately, as a result, many excellent bands oft get overlooked. Among those bands is Shadow Gallery.
What sets Shadow Gallery apart are there church choir-esque vocal harmonies. Where Dream Theater is so heavily focused on musical technique, Shadow Gallery's focus is firmly planted within the realm of harmony-- and it's not just with the vocals (although their vocal harmonies are generally the first thing new listeners notice when first "discovering" this band)-- instrumentally their harmonies tend to be significantly tighter than just about any other metal band (progressive or otherwise) that I've ever heard.
Incidentally it was on the recommendation of a Dream Theater fan that I decided to check out Shadow Gallery. I was not led astray. There was something almost angelic about their harmonies. But when you juxtapose the crunchiness of their guitars with their tight harmonies their music is transcendent.
I realize that one of the complaints many critics have of various forms of progressive rock is that it's overly indulgent and pretentious-- who needs 10, 20, 30 minute songs. Shadow Gallery are gross offenders of that stereotype-- Legacy only has 6 songs on it, 2 of which are over 7 minutes, 1 clocks in at over 15, but the most egregious offender is the 6th and final track, First Light clocking in at 34 minutes 18 seconds (including a 5+ minute "dramatic pause").
First Light is ALMOST a brilliant piece of musicianship which is marred by the aforementioned dramatic pause. Up until the start of that "pause" this is easily one of my favorite CDs... But that "pause" serves no purpose and is a glaring blemish on this otherwise exceptional album-- imagine if you will, a beautiful readhead, perfect in every way except she has a giant mole smack dab in the middle of her forehead with a hair growing out of it. This album is that beautiful redhead and that mole is that wholly unnecessary "pause."
Colors, Legacy, and ESPECIALLY Destination Unknown are some of the most exceptionally crafted songs I've ever heard. The harmonies are spot-on, and while progressive music is notorious for sacrificing emotion for technique-- these songs still manage to evoke some level of emotion in a genre typically not known for doing so.
If you can look past that mole, this beauty has a really great personality.