I think the best bang for your buck comes from 1-Tech DT with pass rushing skills.
That would be Harmon or Grant and we potentially have a shot at one of them.
The other "game wreckers" are probably Abdul Carter, Mason Graham, and Jalen Walker .... maybe Shemar Stewart. We don't have a legitimate chance at any of them unless we trade away too much.
Some people are high on Mike Green (small bendy rusher), Mykel Williams (raw with bad production), and Walter Nolen (3-tech), but I don't like the fit.
To answer the question is: Harmon and Grant because they fit a need and will make everyone around them better. No other true "game wreckers" in range at 30.