Word for a person who likes to argue

Polemic (polemicist) or Controversialist.

polemic (noun): A person who argues or writes in opposition to another, or who takes up a controversial position; a controversialist. Cf. polemicist n. [OED]

polemicist (noun): An author of polemics; a controversialist. [OED]

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controversialist (noun): a person who likes to disagree with other people and say things that make people angry or think about a subject [Cambridge]

You can consider argumentative or contentious as an adjective.

debater
a person who disputes; who is good at or enjoys controversy

eristic
2. a person who engages in disputation
the art or practice or debate or argument

gainsay
Gainsay comes from an Old English word that means "contradict" or "say against," If you know someone who constantly corrects others, tells them that they're wrong, and says, "That's not true," more than anyone else, you have first-hand experience with the art of the gainsay.

_{The Free Dictionary. Vocabulary.com}

"Contrarian" is a good term for someone who always has to bring up a contrary point. I like it because it is neutral, even though the behavior itself can be quite annoying. The noun form gives it dignity, as if there's an important role a contrarian plays in a group.

How about antagonistic? Or maybe, pugnacious.