Allspice is an all-in-one spice
Allspice is the dried unripe fruit of a tree native to the Greater Antilles, Southern Mexico, and Central America. It got its name as early as 1621 from the British who thought it combined the flavor of cinnamon, nutmeg, and cloves. The main producer is Jamaica, and it is, not surprisingly, a major component in jerk rubs. Because it embodies a slew of other spice aromas, stocking allspice is a great way to cut out storing other spices (looking at you, cloves). Allspice has a strong, dominant flavor, so a small sprinkle will suffice. Add it to pumpkin pie or gingerbread, stews, roasted vegetables, and jerk marinades.
Garlic powder, onion powder, and dried herbs are time-savers
Garlic powder and onion powder are respectively dried onions and garlic that are made into powder. You could keep them around, and you should if you need some flavors in a pinch, but neither compares to the real thing. The same goes for dried thyme, rosemary, and oregano, which are herbs, NOT spices. Regardless, fresh is generally better. If you are using dried herbs, they are usually best when added to the beginning of dishes, while fresh herbs fair better when added towards the final stages of cooking. And never, ever buy dried chives or basil as a substitute for their fresh equivalents. Their flavors don't even come close. Just leave them out instead.