Searching for the Young Soul Rebels was among the first that sprang to my mind.
Johnny Burnette and the Rock 'n Roll Trio
The "Chirping" Crickets
Walk Away Renée/Pretty Ballerina (The Left Banke) Songs of Leonard Cohen
The Gilded Palace of Sin (The Flying Burrito Bros.) #1 Record (Big Star) Unknown Pleasures (Joy Division) Fire of Love (The Gun Club) Appetite for Destruction (Guns N' Roses)
All debut albums I struggle to find any defect in.
If we can include solo artists, then Judee Sill's eponymous record is as perfect a debut as I could imagine. Tim Hardin 1 is great. I'm very partial to The-Dream's Love/Hate.