Third Party Support?

(Relatively new Redditor, apologies if this is an old topic) I've recently become immersed in politics. Studying all kinds of philosophy, party history, practices, etc. Standard high school/college U.S. Gov course material. I'm starting to realize how flawed both Republican and Democratic parties are, and I've considered supporting a third party. If you support one, who do you support and why? And is it really worth it, or do you just pick your top issues and support the major party that might enforce them?