re: What is the ranking of these American wars based on how epic they were?

It depends on what you mean by epic. As a whole the two world wars were the most epic, the world had never seen anything like it before and hopefully never will again. For America the Civil War was the most epic. The American Revolution was extremely consequential but I dunno if I would describe as epic. The war with Mexico was also but less globally.

WWI affected Great Britain tremendously and started its decline. France never regained its strength. Germany became Socialist. Russia's ruler was toppled. Italy thought that it could be somebody relevant again. The U.S. got a seat at the table but opted not to participate in the spoils of war. The whole ME thing began when the already weak Ottoman Empire was split up by geography not by ethnic regions.

WWII exhibited the Industrial power of the U.S. and left it unscathed as the rest or the world had its industrial power bombed to smithereens, except USSR which had entire manufacturing plants given to it.

In economic impact WWI set the stage and WWII rearranged the chairs at the table.