I was wondering about how many studio albums other bands have done and if Stones are among the first.Also how many albums for example from Led are considered must have like we consider exile or let it bleed.

I think the question is if other bands have as many GOOD studio albums as the stones...

Of course that depends on how many really high quality studio albums you think the Stones have...

Right off, IMO, Let it Bleed and Sticky Fingers are FIRST RATE studio albums... Exile is a fair album, Beggars Banquet is fair...

Depending on your taste, the Stones probably have 3 to 5 really good studio albums.

IMO there's quite a few bands that have that many.

"It's just that demon life has got me in it's sway..."

Van Morrison has some great studio albums. Here are only the ones I like best:

ST DOMINIC'S PREVIEW
WAVELENGTH
BEAUTIFUL VISION
AVALON SUNSET
THE HEALING GAME
MAGIC TIME

Of course he also has some waek albums (DAYS LIKE THIS, BACK ON TOP) but the others are really good.

As for live albums I'd go for BB King. But similiar to the Stones (Leeds 1971, Brussels 1973, and so on) some of his best live recordings have never been released. But LIVE IN COOK COUNTY JAIL and LIVE IN JAPAN are great.
If his Montreux Jazz Festival recordings were ever released (probably the best are from 1990 and 1993) this would prove again how brilliant BB King was as a performer, even if he didn't change his setlist much.