advantage
ace in the hole, ace up one's sleeve, aid, ascendancy, asset, assistance, avail, benefit, blessing, boon, boot (obsolete) convenience, dominance, edge, gain, good, help, inside track, interest, lead, mileage (informal) precedence, pre-eminence, profit, service, start, superiority, sway, upper hand, use, utility, welfare
Antonyms
curse, difficulty, disadvantage, downside, drawback, handicap, hindrance, inconvenience, snag