In no particular order (except No. 1):
1.) Stairway to Heaven - Led Zeppelin (it may sound trite to some, but it is still the greatest rock song that will ever be).
2.) Hells Bells - AC/DC
3.) Feel Like Makin' Love - Bad Company
4.) Mississippi Queen - Mountain
5.) Street Fighting Man - The Rolling Stones
6.) Voodoo Child (Slight Return) - Jimi Hendrix
7.) Lateralus - Tool
8.) All Day and All of the Night - The Kinks
9.) For Whom the Bell Tolls - Metallica
10.) Back in the Saddle - Aerosmith
Of course, this list could be 100 songs long just as easily as 10.
I would contribute to the country songs thread, but I can't grasp the concept of "best" and "country songs" in the same sentence.