#1 Michael Booth (born c. 1973), journalist, is the author of Just as Well I'm Leaving and other travel books; WorldCat suggests he is also the author of the Guide to Best Family Films.
#2 is Michael R. (Richard) Booth (b. 1931), professor and author of works on 19th century theatre. See separate LT entry for him.
#3 Michael Booth (b. 1975) is the author of Computations on Hyperelliptic Curves.
#4 Michael Booth did the cover for The Classic Philip Jose Farmer (from ISFDB)