First of all, I'm not English. Sorry for some sentences you may not understand.

Tier A:

I feel "Hejira" is her best effort by far. I won't waste words on it.

"For the roses" is a personal taste. I feel she reaches an introspectivity here at the same level as "Hejira". That's the reason I ranked it before "Blue", her most iconic one. Not songs are wrong in these albums. It is amazing how "Blue" sounds. It doesn't seem it is 50 years old. Quite minimalistic, but too deep and ever-lasting.

As for "Court and Spark", I find some too commercial songs (Help me, Raised on Robbery, Free man...) that makes it drop a little. The closing track "Twisted" isn't suitable either.

B:

She nailed it in the folk aspect. The three last songs of "Ladies of Canyon" make it the winner. "Hissing in the summer Lawns" shows Joni wasn't good just at folk music. Lyrics are sublime. 

I feel her first album has better tracks than "Clouds", but the production is worse. Nevertheless, I feel it deserved to he higher since in Clouds there are more forgettable tracka (Blue roses, Tin Angel, the Fiddle and the Drum, aging - dunno why -...).

"Night ride home" could be higher,  but Joni's voice has prevented me from doing that. She returned to folk in a different way, which is fine. 

C:

"Don Juan's reckless daughter" was the beginning of Joni Mitchell's lower quality. Some tracks are quite good, but we cannot deny her voice was losing her high notes and some tracks were repetitive (for instance, compare title track to Coyote) or too ambitious (the tenth world, Dreamland or Paplika Plains).

"Taming the tiger" is underrated at this point. Once again I know this is a quite personal preferences: her guitar skills make this album more memorable than those below it: starting track, Mars from Mars, Stay in Touch, Face lift... are quite formidable tracks.

D:

From now on, I only find some really good tracks among average ones. "Moon at the window" is amazing. She nailed it. The rest of the album "wild things", though, doesn't have a interesting sound (OK, Chinese café is kinda good too).

I don't remember the title of this album (sorry). I know she won a Grammy due to it, but she made really long songs that not always keep compelling for the listener. Maybe I could have ranked it before the previous one. They are quite close. Really enjoyed closing track.

"Both sides, now" is clever since she achieves to renew herself. Nevertheless, it is her own tracks the only one who stand out. Travelogue is the same idea than before. Some weird choices ("for the roses") and some highlights ("Chefokee Louise", "Amelia"...). Nevertheless, she is always better creating new things than recreating them. 

The last sentence is true till this point. "Chalk" album isn't good due to the guests she includes in it and her change of style: in 80s it is clear she struggles with new music style trend and her change of voice", so I cannot avoid to think she is lost here sometimes. I guess she invited these people to make herself notorious again...

As for "shine", I must admit it is the only album of her I didn't finish. I don't find the way to get into it, so I decided to leave it her. "If I had a heart..." is nice, though. If I end it one day, I may rank it higher (or lower).

E:

Joni isn't good at jazz. She could add jazz elements to her albums properly, but it doesn't mean she was apt for this stuff on its own. Some short tracks that add nothing and some songs with weird music patterns.

"Dog eat dog". Not using her guitar at all or barely is the worst she could have made. As I said in "Chalk", she was quite lost in 80s. She could not adapt to changings. Some songs sounds better in live (for instance, Dog eat dog in piano). I'm gonna admit I like "three great Stimulants",though.

All in all, I want to add that when she talks about herself or some compelling story, her work is easier to enjoy, so for that reason albums as Dog eat dog or Chalk get a quite poor rating. 

My tier list after 4 years listening to her