Time is the only resource you can't buy back. Except at the airport.
TSA PreCheck ($78/5 years)
Best For: Domestic US travelers. Keep shoes/laptop on. Essential.
Global Entry ($100/5 years)
Best For: International travelers. Includes TSA PreCheck. Skip the customs line when re-entering the US.
CLEAR ($189/year)
Best For: Frequent fliers at major hubs. Skip the ID check. Stacks with PreCheck.
The Verdict
Get Global Entry. It includes PreCheck and pays for itself in one international trip. Use credit card perks (Amex Platinum/Chase Sapphire) to get it for free.