Personal preferences aside, b/c there's no point in having a discussion because it won't change those, AC/DC is just a better band. Plain and simple. You may like GnR's music more (heck, I think its great), but they don't compare to to AC/DC. Let's review:
Famous concert moment:
AC/DC - First time their lead guitarist steps out in an undersized school uniform, bouncing around on one leg, a moment to be imitated for years to come by many air guitarists worldwide.
GnR - refused to play at all, let alone a little early, to appease crowd after first band, Metallica, has to stop due to severe burns to lead singer. Riot ensues.
Line up changes:
AC/DC - overcame the death of their lead singer while they were at the top of their careers it seemed. Found a new lead singer, and went on to bigger and better success.
GnR - Lead singer alienated himself from the band, and Axl is just plain god awful without Slash and instead this mockery of a band he now calls GnR.
AC/DC - 12: Back in Black, Rock and Roll Aint Noise Pollution, Hell's Bells, Big Balls, Dirty Deeds, For Those About to Rock, TNT, Girls Got Rhythym, Highway to Hell, Moneytalks, Thunderstruck, Who Made Who
GnR - 9: Welcome to the Jungle, Sweet Child of Mine, Paradise City, November Rain, Don't Cry, Civil War, Patience, Knocking on Heaven's Door, Live and Let Die
(Mind you I'm trying not to include anything great but relatively obscure like "Whole Lotta Rosie" or "Used to Love Her").
I dont think I need to bring up survivability to anyone. GnR was a flash in the pan, a great big brilliant flash, but when all is said and done, they had one great album, and 2 very good ones, whereas AC/DC lasted over three decades, and still draws a crowd.
Appettite For Destruction may have been one of the best albums ever put together, but I could say the same about Sixteen Stone, but its still just one album.