They've stated this on a few occasions. Here are some recent links.

Johnny Marr:

Johnny Marr Remembers the Smiths' Studio Albums | SPIN | Interviews

Morrissey:

Morrissey’s Top 10 albums by Morrissey and The Smiths: The records ‘of which I am most proud’

I can sort of see why, it is their most mature album production wise, and I think its a great release but even Johnny Marr bows to the wisdom that the Queen is Dead is their best, lol.

Anyhow

Disintegration 7
Queen is Dead 7

Same, actually! I love the rest of the album but I will always be in the mood for Shankly. The smarmy lyrics are the best.
I'll abstain from this because I haven't heard any Cure.

What?!

The guy only listened to Wonderwall like two months ago. Nothing surprises me any more.

If it softens the blow at all, I hadn't heard Wonderwall until last month or so, so just assume that if something's important to music history that I have neglected to listen to it.
EDIT: HA Goofle beat me to it.

Disintegration 7
Queen is Dead 8

In a lot of ways, I feel like Meat is Murder and the Queen is Dead are complementary albums. I feel like they match song-for-song in terms of tone and quality. I find it difficult to pick between them for favourite, but the Queen is Dead came first for me, so it'll always outshine Meat like a firstborn child.

I'm still freaking out about this like I said not hearing Wonderwall is like never seeing the colour red or something

How do you not hear Wonderwall if you were born in the 90s.

I've sung that song one too many times at Karaoke.

The blow has not been softened.