Only including governors since statehood would be the proper approach since it's an elected office, unlike their predecessors.  Pre-statehood governors were appointed by the president and most of them answered directly to the Interior secretary.  If you take a close look at Wikipedia's coverage of Alaska's governors, you can see that a greater amount of emphasis is placed on governors when compared to other aspects of Alaska.  Unfortunately, it's mostly due to outsiders who are far more concerned with the office itself than they are with any of the people who held the office.