That said, for me the best debut LPs are the ones pre-Beatles/Stones.
The best debut albums are post '65-'66, because that's when the market fully shifted from singles to albums-orientated.
The Velvet Underground - Velvet Underground & Nico
Pink Floyd - Piper at the Gates of Dawn
Jimi Hendrix Experience - Are You Experienced?
The Band - Music From Big Pink
Jeff Beck Group - Truth
Black Sabbath - Black Sabbath
King Crimson - In The Court of the Crimson King
Ramones - Ramones
Guns N' Roses - Appetite for Destruction
N.W.A - Straight Outta Compton
Pixies - Surfer Rosa
Portishead - Dummy
Oasis - Definitely Maybe
Eminem - The Slim Shady LP
Janelle Monae - The ArchAndroid