Glover. He has earned his shot and Gus is best off getting another win or two before challenging for the title again.
Glover has great TDD and could force Bones to stand with him, if not take Jon down himself. He's got a very well-rounded skillset and hits as hard as any 205er. That would be a fantastic matchup.
Glover would have a much harder time closing the distance than Gus, no question. You'll see people on Sherdog say Glover will kill Jones merely because he had a close fight with Gus. Even some fighters (Machida) are picking Glover to beat Jones, just because they want him to lose.