If you are settled on something from those three, you basically have them in order... McPherson's "Battle Cry of Freedom" is a bit old at this point, but still a very solid book, and hard to beat for a single volume over view of the conflict. To be sure, scholarship hasn't been overturned since the 1980s, and there is nothing significant in there that is utterly out of whack with more recent consensus. It is the one I recommend for the "just one book!" requests, and I haven't yet encountered something that has supplanted it.

I haven't read Gallagher's book, but I am familiar with other works of his, and he is also a fantastic historian, so I would feel comfortable saying that if his more specialized volumes are any indication, any single-volume overview by him should be a decent read.

Now as for Foote... I admit I have a soft-spot for him. His prose is just gorgeous and he paints a picture that draws you in an a way you won't find in, well, any other history of the war. But it is also a very dated work that absolutely does not reflect more recent scholarship. It is something of the pinnacle of the old, conventional wisdom, Lost Cause tinged "War Between Brothers" perspective that dominated the early 20th century and can't be found in just about anything academic published in the past 40 or so years. I actually do still think it is worth reading, but definitely not as an introduction. Its important historiographically for what it represents as the above, and also, once you have a better grounding to know when to look at it cockeyed, like I said, it is just enjoyable to read.

Not so much about battles and dates, but about the man and how he prosecuted the war and lead the nation. Highly recommend.

Tried by War: Abraham Lincoln as Commander-in-Chief by James M. McPherson