Well, my favorite album is "The Lamb Lies Down on Broadway" so for that reason I have to give major recognition to 1974.
But 1967 was the best year for rock music, as long as we're not using that narrow definition of rock that would exclude the Beatles, or the idea of rock only being "hard rock" (and not psychedelic rock, pop rock, folk rock, art rock, etc. etc.).
I mean, Come On:
The Beatles - Sgt. Pepper AND Magical Mystery Tour
Jimi Hendrix - Are You Experienced? AND Axis: Bold as Love
Cream - Disraeli Gears
The Doors - The Doors AND Strange Days
Jefferson Airplane - Surrealistic Pillow
The Who - The Who Sell Out
Janis Joplin / Big Brother and the Holding Company
Pink Floyd - The Piper at the Gates of Dawn
The Velved Underground - The Velvet Underground & Nico
Love - Forever Changes
The Moody Blues - Days of Future Passed
The Rolling Stones - Their Satanic Majesties Request AND Flowers AND Between the Buttons
Procul Harum - Procul Harum
Buffalo Springfield - Buffalo Springfield Again
Moby Grape - Moby Grape
And these are just some of the most obvious - hardcore music-philes will know that there are a couple dozen other classics from the year.
This doesn't even include some fantastic jazz and blues releases, such as "Born Under A Bad Sign" by Albert King, and "Nefertiti" by Miles Davis, and great soul releases by Otis Redding, James Brown and Aretha Franklin, to name a couple. But even without this not-quite-rock stuff, the year is still amazing.
I know these aren't all necessarily the best albums by some of these artists ("Flowers" is no "Let It Bleed") but on the whole I don't think any year ever produced more truly great, classic albums. Just the top four artists' releases on the above list are practically enough to make 1967 the best year in rock history.