Degree & Limitation: のみならず vs はもとより vs どころか vs ないまでも
Three of these escalate in the same direction; どころか is the only one that reverses. ないまでも is a different animal entirely — it lowers the bar rather than raising it.
The patterns
のみならず
not only ~ but also (plain escalation)
彼は学者のみならず、優れた教育者でもある。
He is not only a scholar but also an excellent educator.
はもとより
to say nothing of ~ (A is too obvious to mention)
国内はもとより、海外でも人気がある。
Popular abroad, to say nothing of at home.
どころか
far from ~ ; on the contrary
暖かいどころか、真夏のような暑さだ。
Far from warm — it was as hot as midsummer.
(とは言わ)ないまでも
even if not quite ~, at least
プロとは言わないまでも、それなりの実力は身につけたい。
Even if not professional level, I want real ability.
Decision procedure
Does the second half continue in the same direction, or reverse it?
Are you lowering the bar (falls short of A, but at least B)?
Are you stressing that A is so obvious it barely needs saying?
Commonly confused
ものではない — two different meanings
With a volitional verb in dictionary form it is a moral admonition ("人の悪口を言うものではない" = you shouldn't speak ill of others). With a potential form or a state description it shifts to denying an inference ("株を買えばすぐに受け取れるものではありません" = buying shares doesn't mean you receive them immediately). Check which verb type precedes it.
Kana vs kanji is itself a signal
Many grammar particles descend from content words with kanji (ところ←所, もの←物/事, まで←迄). Japanese convention drops the kanji once the word becomes purely grammatical. So kanji spelling usually means literal meaning; kana spelling usually means grammatical function.