I love them as much as I love Bon Jovi. To me their musical outputs can be compared pretty well although sales wise DL isn't as fortunate as BJ. A BJ/DL double headlining concert would be awesome for me.

I have all their albums. If I were to rank 'em (excluding Vault) it would go like this:

1. Hysteria. I know the production may turn some rock fans off, but I think, technically the production is flawless from top to bottom. Plus, the songs are strong. Pour Some Sugar On Me is the worst song in the album and it's still pretty good. That's how great the album is.
2. Euphoria. I rank this album so high because it came in 1999. Nothing sounded like that in 1999. Very ballsy for the band to release a 80s sounding record in that time. Promises has one hell of a hook. The only weak spot in it is the crap All Night. Even She's A Mystery is better than this nonsense.
3. Pyromania. You should know the hits but album tracks like Stagefright and Rock Rock rule the live setting. Excellent. The only weak spot is Billy Got A Gun (and I was unlucky enough to hear it live once).
4. Retroactive. This is a B side compilation but ALL songs in it are worthy of A side. No weak song at all.
5. High N Dry. The first 5 songs just kick so much ass. Too bad I didn't get to hear them live when I saw em recently.
6. Adrenalize. Critics panned this album but you know when critics say bad things about a rock album, then the album must be good. Some lousy lyrics but the songs are fun. Have You Ever Needed Someone So Bad is one of the best rock ballads ever.
7. X. Too poppy for me. You're So Beautiful, Scar and Long Long Way To Go are the definite highlights. The rest are okay. Now is kinda lame, and Gravity is WAY lame.
8. On Through The Night. Wasted is a classic and MUST be played in all DL concerts.
9. Slang. I'm all for experimentation but like everythingg else, an experiment can either be successful or not. The way I feel about this album is the way I feel about These Days: I think they are not good and since 'die hard fans' love to praise them, it makes them even worse (overrated) in my eyes. Beside Gift Of Flesh, Truth, Breathe A Sigh and Where Does Love Go, the rest are crap.

Def Leppard seriously need to release a live album. And it should NOT be like One Wild Night.