where does it figure best to worst MCU?

Well, knowing that a best of list is different with everyone, Black Panther will probably end up all over the place.
Personally, I think it will be along the lines of Iron Man and Captain America

1. Guardians of the Galaxy
2. Captain America: Civil War
3. Doctor Strange
4. Guardians of the Galaxy: Vol. 2
5. Black Panther
6. Captain America: The First Avenger
7. The Avengers
8. Iron Man
9. Thor: Ragnarok
10. Captain America: The Winter Soldier
11. Thor
12. Spider-Man: Homecoming
13. Avengers: Age of Ultron
14. Iron Man 3
15. Thor: The Dark World
16. Ant-Man
17. Iron Man 2
18. The Incredible Hulk

1. The Avengers
2. Captain America: Civil War
3. Captain America: The Winter Soldier
4. Iron Man
5. Avengers: Age of Ultron
6. The Incredible Hulk
7. Spiderman: Homecoming
8. Captain America: The First Avenger
9. Guardians of the Galaxy
10. Black Panther
11. Thor: Ragnarok
12. Iron Man 2
13. Ant-Man
14. Thor
15. Doctor Strange
16. Guardians of the Galaxy: Vol. 2
17. Iron Man 3
18. Thor: The Dark World

1. The Avengers - 9/10
2. Guardians of the Galaxy - 8/10
3. Guardians of the Galaxy Vol. 2 - 8/10
4. Thor: Ragnarok - 8/10
5. Iron Man - 8/10
6. Captain America: The Winter Soldier - 7/10
7. Doctor Strange - 7/10
8. Captain America: Civil War - 7/10
9. Ant-Man - 7/10
10. Thor - 7/10
11. Iron Man 3 - 7/10
12. Spider-Man: Homecoming - 7/10
13. Captain America: The First Avenger - 7/10
14. Avengers: Age of Ultron - 6/10
15. Black Panther - 6/10
16. The Incredible Hulk - 6/10
17. Iron Man 2 - 6/10
18. Thor: The Dark World - 6/10

Best I can do is group them into tiers. Within the groupings they aren't in any kind of order.

The best two films:

Spider-Man: Homecoming
Captain America: The Winter Soldier

The excellent films:

The Avengers
Thor: Ragnarok
Guardians of the Galaxy
Ant-Man
Captain America: Civil War
Black Panther

The very good films:

Iron Man
Iron Man 2
Thor
Avengers: Age of Ultron
Guardians of the Galaxy Vol. 2
Doctor Strange

The films I thought were flawed but good:

Captain America: The First Avenger
The Incredible Hulk

My least favorite, but still enjoyable, films:

Thor: The Dark World
Iron Man 3

Yeah, I prefer to group them into tiers as well

A+
----------------------------------------
Captain America: The Winter Soldier
The Avengers
Guardians of the Galaxy

A
-----------------------------------------
Black Panther
Captain America: Civil War
Thor: Ragnarok

B+
-----------------------------------------
Iron Man (Could move this up a tier but never been that much of a Iron Man fan)
Spider-Man: Homecoming
Guardians of the Galaxy: Vol. 2
Doctor Strange

B
------------------------------------------
Captain America: The First Avenger
Thor
Avengers: Age of Ultron
Iron Man 3
Ant-Man

C+
------------------------------------------
Iron Man 2
The Incredible Hulk
Thor: The Dark World

--------------------------------------------
EXCELLENT

Guardians of the Galaxy
Captain America: The Winter Soldier
The Avengers
--------------------------------------------
VERY GOOD

Thor: Ragnarok
Iron Man 3
--------------------------------------------
GOOD

Thor
Guardians of the Galaxy: Vol. 2
Ant-Man
Doctor Strange
HULK
--------------------------------------------
AVERAGE

Black Panther
Captain America: The First Avenger
Iron Man
Spider-Man: Homecoming
--------------------------------------------
NOT GOOD

Avengers: Age of Ultron
The Incredible Hulk
Iron Man 2
--------------------------------------------
BAD

Captain America: Civil War
Thor: The Dark World
--------------------------------------------

Quite a disparity in the rankings. I'm especially surprised at how low Spider-Man: Homecoming is appearing on many people's lists. Only Iron Man and Black Panther received higher critical acclaim, and it was huge hit with audiences. Personally I think it's more or less tied with The Winter Soldier as the best MCU film to date, and I can't quite grasp how, for example, someone ranked it 12th, or another labeled it average. Even if someone isn't a fan of Spider-Man, the movie itself was, well, amazing, and is one of very few comic book films, in my opinion anyway, that transcend the genre.