I concur with the general consensus here that, while Boy is a memorable, unique and special first album, it's a bit of an odd choice for the (entirely trivial) #1 spot on such a list. The list-makers should know the can of worms they're opening up for themselves by ranking anything U2-related at #1!!!
Even trying to be objective about it, I think the #1 spot should go to more of a classic-rock artist who peaked earlier (unlike U2) and who was more musically accomplished on the first album (unlike U2). (By this criterion, the real classic first album in the United States was Meet The Beatles, but it was actually their 2nd American album).
I also agree that The Stone Roses, which is my favourite first album, is a no-brainer for a list like this, and its absense is baffling (obvously, this is an American list).
Here are my thoughts on some of the top-50:
2. Miles Davis - Birth of the Cool
WTF?? This is not Miles' first album by any stretch of the imagination; it is his first with Gil Evans and the nonet, but hardly his first. I got this one when I was 18 or so -- certainly a great recording, but why does every rock list feel obligated to include Miles Davis and Coltrane? Why include jazz at all, and if so, why not Ella Fitzgerald and Bill Evans and Weather Report? Ridiculous.
4. Led Zeppelin - Led Zeppelin
Like many people with a university degree (or more than one), I dislike Led Zep. I'll give them some props for being loud and musical. But they certainly weren't original at all, so I think this is way too high (if it's up to me, they wouldn't be on here at all).
7. Nirvana - Bleach
Clearly, this is here because of their next two albums -- which means it shouldn't be here at all.
8. Bob Dylan - Bob Dylan
I'm a major Dylan fan, and even I think this is absurd. Dylan himself disowned his first album before it was even released!
9. Metallica - Kill 'em all
The title pretty much sums up my feelings towards the members of Metallica.
10. Arcade Fire - Funeral
Again, even though I'm Canadian, I think these guys (and gals) are the most overrated thing since the new Coke. Check back in 20 years when they've been completely forgotten on lists like this.
11. Jay-Z - Reasonable Doubt
I love Jaz-Z, but if you're gonna put a hip-hopper near the top, you've gotta choose an old-skool guy or group. This is as silly as putting . . . I dunno, U2 ahead of The Beatles! Oh, wait...
16. Brian Eno - Here Come The Warm Jets
And there go the record buyers!
17. Elvis Presley - Elvis Presley
This should be #2 or #3.
20. New Order - Movement
I love the New Order guys, but giving them two in the top 20 when The Beatles have 0? Say goodbye to credibility. . .
23. Kanye West - The College Dropout
See Arcade Fire. Better yet, Kanye, see a psychologist for suppression of the ego.
29. John Coltrane - Coltrane
See Miles Davis nonet above. This isn't even one of Trane's better albums.
32. the Doors - The Doors
This should be a lot higher on the list.
33. Jimi Hendrix Experience - Are You Experienced?
Should be in the top 5.
44. Snoop Doggy Dogg - Doggystyle
45. Vicente Fernandez - A Pesar De Todo
46. A Tribe Called Quest - Peoples' Instinctive Travels & the Paths of Rhythm
47. Nas - Illmatic
#44 through #47 are pretty much all forgettable. . . and I even like A Tribe Called Quest!
50. Liz Phair - Exile in Guyville
I was the first one amongst my circle of friends to own this album . . . so there! (Yes, it's great -- but how the mighty have fallen.)
In conclusion: Move U2 down the list, bring Elvis and Jimi way up, get rid of instrumental jazz which shouldn't be compared to rock and roll, get rid of the stuff that nobody cared about in the first place (Brian Eno), get rid of artists who are there because they're great but not there because of their debuts (Nirvana, Bob Dylan), add Please Please Me, The Stone Roses, some Motown-ers with great first LPs, Bjork's Debut, and Sinead O'Connor's Lion and The Cobra, and then we'll talk. . .