more/most correct

It depends on which meaning of "correct" you are using, and whether you are applying it to single items or groups or collections of items.

Sometimes correctness can be partial, and then it makes sense to have notions of things being more or less correct, or of a thing being the most correct.

Sometimes "correctness" can be a matter of opinion. This is particularly true of some aspects of English usage.

An essay or sentence or a set of exercise answers could be partly or mostly or altogether correct, and a comparison of such items from different students might reveal whose was most correct.

Definitions of correct (adj) on the Web:

* free from error; especially conforming to fact or truth; "the correct answer"; "the correct version"; "the right answer"; "took the right road"; "the right decision"

* socially right or correct; "it isn't right to leave the party without saying goodbye"; "correct behavior"

* in accord with accepted standards of usage or procedure; "what's the right word for this?"; "the right way to open oysters"

* right: correct in opinion or judgment; "time proved him right"

Beware of becoming obsessed with "correctness", Yoong Liat, if you wish to attain true fluency. English is not mathematics.

Thanks for your clear and detailed reply. I appreciate it very much.

Thanks for telling me that English is not maths. I'm fully aware of it. However, I'm obsessed with prescriptive English, while some who cannot have a good command of English in terms of grammar and word usage will mostly like say I go for descriptive English.

All the best.

Obsession is decidedly not a good thing. It has implications of over-attentive interest in detail at the expense of the wider picture, and of unappealing and counter-productive mental rigidity. That is just my opinion.

Did you mean to write,

I'm obsessed with prescriptive English, while some who cannot have a good command of English in terms of grammar and word usage will mostly like to say "I go for descriptive English."?

If you are suggesting that those on the descriptivist side of some imaginary line are there because of laziness and imperfect grasp of language, then you are gravely and deeply in error.

I do not feel that your command of English is yet sufficiently great for you to have the right to take up such a position. (Actually, I do not feel that anybody has such a right.)

The trouble is, people take up such positions at least in part because of their attitudes to life itself -- what else is language but the means to live life? -- there are those people who love to think that there should be unchallengeable "rules" which should definitely govern use of language, and there are those who feel that a grammarian's job is to record and describe as well as (not instead of) guide and advise. That is just my opinion also.