John 3:16 – Use of the word “should” instead of “would”, “will not”, “could not”, “cannot”, or some other word. 

Should – Usage notes:

Like the rules governing the use of shall and will on which they are based, the traditional rules governing the use of should and would are largely ignored in modern American practice. Either should or would can now be used in the first person to express conditional futurity: If I had known that, I would (or somewhat more formally, should) have answered differently. But in the second and third persons only would is used: If he had known that, he would (not should) have answered differently. Would cannot always be substituted for should, however. Should is used in all three persons in a conditional clause: if I (or you or he) should decide to go. Should is also used in all three persons to express duty or obligation (the equivalent of ought to): I (or you or he) should go. On the other hand, would is used to express volition or promise: I agreed that I would do it. Either would or should is possible as an auxiliary with like, be inclined, be glad, prefer, and related verbs: I would (or should) like to call your attention to an oversight. Here would was acceptable on all levels to a large majority of the Usage Panel in an earlier survey and is more common in American usage than should. - Should have is sometimes incorrectly written should of by writers who have mistaken the source of the spoken contraction should've.[1]

Rather: USAGE NOTES:

In expressions of preference rather is commonly preceded by would or in formal style should: We would rather rent the house than buy it outright. I should rather my daughter attended a public school. The use of had in these constructions may now be more infrequent than it once was but is still encountered in reputable writing: I had rather be dead than be a slave. This use of had was once widely criticized as a mistake, the result of a misanalysis of the contraction in sentences such as I'd rather stay. But it is in fact a survival of the subjunctive form had that appears in constructions like had better and had best, as in We had better leave her alone. (Notice that in these constructions would and should cannot be used.) This use of had shows an unbroken line of usage running back to Middle English, and traditional criticisms of these constructions are unfounded. - Before an unmodified noun only rather a is used: It was rather a disaster. When the noun is preceded by an adjective, however, both rather a and a rather are found: It was rather a boring party. It was a rather boring party. When a rather is used in this construction, rather can be construed as qualifying only the adjective, whereas with rather a it can be construed as qualifying either the adjective or the entire noun phrase. Thus a rather long ordeal can mean only "an ordeal that is rather long," whereas rather a long ordeal can also mean roughly "a long process that is something of an ordeal." Rather a is the only possible choice when the adjective itself does not permit modification: The horse was rather a long shot (not The horse was a rather long shot). [2]

Shall – Usage Notes: 

The traditional rules for using shall and will prescribe a highly complicated pattern of use in which the meanings of the forms change according to the person of the subject. In the first person, shall is used to indicate simple futurity: I shall (not will) have to buy another ticket. In the second and third persons, the same sense of futurity is expressed by will: The comet will (not shall) return in 87 years. You will (not shall) probably encounter some heavy seas when you round the point. The use of will in the first person and of shall in the second and third may express determination, promise, obligation, or permission, depending on the context. Thus I will leave tomorrow indicates that the speaker is determined to leave; You and she shall leave tomorrow is likely to be interpreted as a command. The sentence You shall have your money expresses a promise ("I will see that you get your money"), whereas You will have your money makes a simple prediction. - Such, at least, are the traditional rules. But the distinction has never taken firm root outside of what H.W. Fowler described as "the English of the English" (as opposed to that of the Scots and Irish), and even there it has always been subject to variation. Despite the efforts of generations of American schoolteachers, the distinction is largely alien to the modern American idiom. In America will is used to express most of the senses reserved for shall in English usage, and shall itself is restricted to first person interrogative proposals, as in Shall we go? and to certain fixed expressions, such as We shall overcome. Shall is also used in formal style to express an explicit obligation, as in Applicants shall provide a proof of residence, though this sense is also expressed by must or should. In speech the distinction that the English signal by the choice of shall or will may be rendered by stressing the auxiliary, as in I will leave tomorrow ("I intend to leave"); by choosing another auxiliary, such as must or have to; or by using an adverb such as certainly. - Many earlier American writers observed the traditional distinction between shall and will, and some continue to do so. The practice cannot be called incorrect, though it may strike American ears as somewhat mannered. But the distinction is difficult for those who do not come by it natively, and Americans who essay a shall in an unfamiliar context run considerable risk of getting it wrong, and so of being caught out in that most embarrassing of linguistic gaffes, the bungled Anglicism. [3]

Better – Usage Notes:

The phrase had better is acceptable, as long as the had or its contraction is preserved: You had better do it or You'd better do it, but not You better do it. [4]