Marine and buzz cuts not that common outside the USA for commercial pilots. Most common cuts range from the ex military 'short back and sides', (nothing like as short as a Marine haircut), through the range to a fully styled head of hair that costs a small fortune to maintain. Companies I have worked for have required the men's hair to be 'neatly trimmed and free of the collar' In this crazy PC world we are now in the rules may be more relaxed, the concept of 'uniform' doesn't always sit well with the younger generation of pilots, many of whom are paying their own way into the business.