It's mainly a matter of taste. Theoretically, since the drop-off in player values is greatest at the top, the earlier picks have a slight advantage, but that's narly negligible.
With the 7th pick, you'd be able to draft a better franchise-caliber player and wouldn't have to wait so long between picks; with the 15th slot, you'd be in a better position to start runs and influence the draft with two picks so close together.
Go with your personal preference. If you like being higher, make the switch.