I put GnR just because that was part of the argument with my friend. And I said WS, Strokes, U2 and Rolling Stones because your bro said "last rock" band, while there are still a lot left. White Stripes will be remembered, as Jack White is probably the most talented musician of today. Motley Crue...I guess. Look Sonic Youth up.
Oh, well, last Rock... I think he meant 'last to come into existance.' Aerosmith still exists, too, and his three favorite are GnR, Aerosmith, and Led Zeppelin. But I'll agree with him on this: GnR were the last true Rock band to come into existance. What we have now isn't exactly Rock anymore. As for the White Stripes... they're already on their way out. There are many, many guitarists that are better than he is... in fact, I wager my little brother (okay, I should stop calling him 'little'... 'younger' is a better term. He's 6'6, has hair half-way down his back, works at a guitar store, knows seemingly everything about Rock and guitars, so it's probably misplaced to say 'little'), I wager my brother is a better guitarist, technically and creatively. I could be mistaken, but I seem to recall my brother saying many times how abysmal Jack White is at guitar - and my brother DOES know what he's talking about. He's not just some kid who likes learns a few chords and thinks he's a guitar genius. He can play most anything, on electric, acoustic, and classical. Heck, he even looks like a true Rocker!