Greatest debut album

Van Halen

Inner Mounting Flame imho does not qualify as a debut. John McLoughlin did two LPs on Douglas - after he left Miles’s Bitches Brew band, before he formed the Mahavishnu Orchestra. 

My best debut LPS would be, in no particular order, excepting The Doors which for me is a clear Numero Uno:

The Doors - The Doors
Laura Nyro - More Than a New Discovery
Jeff Buckley - Grace
Little Feat - Little Feat
Mark Almond Band - Mark Almond Band
Joni Mitchell - Songs of the Seagulls
It’s a Beautiful Day - It’s a Beautiful Day
Crosby Stills Nash - Crosby Stills Nash
David Crosby - If Only I Could Remember My Name
The Byrds - The Byrds
The Flying Burrito Brothers - The Guilded Palace of Sin
Gram Parsons - GP (unless you think of The FBBs as a Gram Parsons backup band, which imo they are not: Chris Hillman was a huge contributor)
Public Image Limited - Public Image Limited
The Gang of Four - Entertainment!
X Ray Spex - X Ray Spex (a one hit wonder, I am afraid)
Scraping Fetus Off the Wheel - Nail
Chicago - Chicago
Hot Tuna - Hot Tuna

The Byrds debut album is not self titled. 
It’s “Mr. Tambourine Man”
Nor is Chicago’s debut album. 
It’s “Chicago Transit Authority”.

Wcfeil you are correct.

At 64 years of age, the brain cells are dying by the trillions as I write this. By the time I hit post, I’ll be ready for assisted living.

Add to the fact fact that I have 6,000 LPs, excuse me if I don’t remember all the titles like I once used to.

“The Byrds” was actually the title of their 1973 reunion album on Asylum.  

David Geffen offered them a boatload to do it.