I doubt Ohio will be the last to be called, unless it's within 1%. The votes get counted more quickly than in other states. Factoring in the time of poll closing/speed of results...
Alaska (since it's the last to close, and counts its results slowly)
Arizona
Georgia
Iowa
NE-02
Despite the time difference, Alaska usually gets called for the GOP fairly quickly. Is there any reason to think it will be close this year?
Trump
And Johnson. He'll probably get at least 10% there, which could add a good amount of uncertainty.