Learn English – Word or phrase for someone who annoys you as soon as they walk in and start talking

Also consider:
• opinionated, “Having very strong opinions” and, in the form self-opinionated, “Holding to one's own opinion obstinately, stubbornly and unreasonably”
• loudmouth or blowhard, “One who talks too much or too loudly, especially in a boastful or self-important manner”
• obnoxious (unpleasant, offensive, annoying, odious)
• eristic, “One who makes specious arguments; one who is is disputatious”
• bigoted, “having or revealing an obstinate belief in the superiority of one’s own opinions and a prejudiced intolerance of the opinions of others”
• egotist, “A person who believes in his own importance or superiority”
• bumptious, “Obtrusively pushy; self-assertive to a pretentious extreme”
• self important, “Having, or behaving as if having, too high an opinion of one's own importance”
• solipsist, “One who adheres to self-absorption and an ignorance of the views or needs of others”
• smart aleck or smart ass, “One who is pretentious about their own cleverness or knowledge; a know-it-all”
• wiseacre, “One who feigns knowledge or cleverness; an insolent upstart”; also “(obsolete) A learned or wise man”

Three of the above appear in Is there a word for a person who doesn't think the rules apply to him?. Also see:
• What's a word for an instance in which one has an opinion about something without having tried it?
• "Arrogant" vs. "conceited"
• A polite substitution for "lamer"
• Someone who forms their own opinion
• Ignorantly dishonest
• Is there a word to describe someone who tends to disagree with others only to upset them?.

Someone suffering from tall poppy syndrome.

Tall poppy syndrome (TPS) is a pejorative term primarily used in the UK, Canada, Australia, New Zealand and other Anglosphere nations to describe a social phenomenon in which people of genuine merit are resented, attacked, cut down, or criticised because their talents or achievements elevate them above or distinguish them from their peers.

eg.

Sue was suffering from tall poppy syndrome. After her cousin Kathy landed a high paying modeling job in New York, she complained loudly at the family gathering about how 'Kathy thinks she's so much better than us now that she's working in New York. Pity it's not going to make her an any nicer person'.