During the Trojan War Athena mocked Ares for daring to challenge her and he lost. Heracles beat Ares once or twice and in one tale when so far as to strip him of his armor. He ran from Typhon. He was defeated by the Alodai. Apollo beat him in a boxing match. Zeus clearly would not be afraid of him and I cannot see Poseidon being either.
About the best I can think of is in one obscure myth he defeated a giant who was considered a great enemy of the gods.
Forgot about that Boxing match! Nice! My case is that Thor was a top tier Deity well Ares was second tier, feared by mortals yes, but what god was'nt? Thor should be at a higher level, and if worship meant anything Thor should be the most powerful heto god there is, as he was also worshiped by farmers and poor folk, he was worshiped by all, with no need of sacrifice, yup being labled a god of war means squat to a Norse God! Not to mention the Thundergod is almost always the most powerful deity in any pantheon, or second.