Right now, the cheapest time of year to travel to Incheon is December/2019. You will pay the most in November/2019.
Asiana Airlines and Korean Air fly direct from the United States of America to Incheon.
China Eastern is the cheapest airline to fly from the United States of America to Incheon.
Qatar Airways is the best airline to fly between the United States of America and Incheon. If you need direct flights then Asiana Airlines is best.