Hello again! I agree with the fellow whose name I can't say or type...the five variations of the second clause of your sentence (must, should, got to, have to, need to) are perfect and lovely. :)
However, in American English, it is much more common to "ask a favor OF" someone, rather than ask a favor "FROM" someone.
I don't quickly find a grammar reference that says "ask a favor FROM" is actually wrong, but "ask a favor OF" gets my vote as the phrase of choice in dominant usage.
If the word "from" is used, it it would usually be if the person is "asking FOR a favor FROM" someone.
"I need to ask a favor of you."
"I need to ask for a favor from you."
But maybe this is American usage? Or maybe the parts of the USA I've lived in? Maybe the Brits would differ?