I expect pronunciation largely boils down to regional and personal preferences.
The "Mac" prefix means "son of" and "Mc" is an abbreviation of that. The "a" is schwa and where I grew up, is pronounced with a short I, as "mick". But I have heard others pronounce it "mack". The McDonalds ads on TV and radio seem to try to split the difference by pronouncing it "meck".
It's also possible that some people go out of their way to say "mack" in an attempt to acknowledge and avoid the "mick" slur that was sometimes used in England and in the US against Irish and Scottish immigrants.
The "Mac" prefix means "son of" and "Mc" is an abbreviation of that. The "a" is schwa and where I grew up, is pronounced with a short I, as "mick". But I have heard others pronounce it "mack". The McDonalds ads on TV and radio seem to try to split the difference by pronouncing it "meck".
It's also possible that some people go out of their way to say "mack" in an attempt to acknowledge and avoid the "mick" slur that was sometimes used in England and in the US against Irish and Scottish immigrants.