Depends on your 'stash, but I'd probably go for the long term disability only on that list. AD&D is just another way of dying really and you should keep enough life insurance for it, regardless of cause of death. LTC isn't worthwhile til your 50s/60s, especially an employer based plan, since it's quite unlikely you'd need to go to a nursing home directly from working (physical therapy/rehab should be covered by your health insurance, not LTC insurance).
If the $500k is enough life insurance for you, then that's fine. If not, buy a new policy outside your employer. Since if you become too sick to work and are terminal, you may lose your employer based policy, same problem as the LTC insurance.