Personally, I can't stand 95% of the country songs out there. There are a few that I actually like though.
Rock is my thing. A lot of the new rock is a bunch of crap though. 90's alternative and late 90's rock is definitely my favorite. Nirvana, STP, old Green Day, Pearl Jam, Offspring, and Chili Peppers are probably my favorite. I do enjoy some rap (If you can get by the swearing). Eminem is awesome with words and can tell a story with his lyrics.
You can never go wrong with southern rock though. My father was always into it when I was growing up and I still enjoy it. There aren't too may people that don't like it.