Many literary critics consider James Joyces Ulysses (1922)

Many literary critics consider James Joyce’s Ulysses (1922), a novel once banned as an obscene one, as the greatest novel of the twentieth century due to its remarkable synthesis of mythology, philosophy, and social realism.

(A) a novel once banned as an obscene one, as
It should be "to be".

(B) which is a novel that was once banned as obscene, as
same problem as above.

(C) once banned for its obscenity as a novel, to be
"as a novel" is awkward.

(D) once a banned and obscene novel, to be
This is better than C, I don't see any issues with it. Lets keep this one.

(E) a novel once banned as obscene, to be
Ok, this is superior to D so this looks like our winner.

I believe E is the right answer.

Many literary critics consider James Joyce’s Ulysses (1922), a novel once banned as an obscene one, as the greatest novel of the twentieth century due to its remarkable synthesis of mythology, philosophy, and social realism.

We need to make a choice between Consider X as Y vs Consider X to be Y split.
Though Consider X Y is preferred choice but here we don't have that option.
Second is the modifier of Ulysses. In each option we have some variations, so lets check them -

(A) a novel once banned as an obscene one, as - Incorrect
once banned as an obscene one - one is redundant

(B) which is a novel that was once banned as obscene, as
no issues but it is wordier because of using 'which is'
(C) once banned for its obscenity as a novel, to be - Incorrect
was it banned for its obscenity because it was a novel? meaning is distorted here.

(D) once a banned and obscene novel, to be
Parallelism - once a banned novel and once a obscene novel - so is it not obscene now? - Incorrect
(E) a novel once banned as obscene, to be
No issues
so between option B and E - I chose E as the modifier is more precise
Answer E

Hello my friend

Manhattan GMAT cites "consider as" as being definitely wrong, and "consider to be" as being suspicious enough to make you question the correctness of an answer choice, but does not consider its usage definitely wrong.

Hope it helps

OFFICIAL EXPLANATION

The correct answer is (E).

In the original version, the phrase an obscene one is wordy. Also, the correct idiom is either consider. . . to be or simply consider, not consider. . . as. Although choices (C), (D), and (E) each corrects both of these problems, choices (C) and (D) are awkward and confusing. Of the three, choice (E) provides the clearest and most graceful sentence.