Arteta proved he was good at deep, creative CM for about 3 months last season. Yes he was quality, but he does not have the pedigree of Alonso.
Iniesta is an attacking midfielder, Craccer, Alonso is a playmaking CM like Xavi and Fabregas.
I personally can't name more than 2 players better than Alonso in his position. He is world-class and was the heartbeat of the Liverpool team last season. Benitez was a fool to piss him off.
Actually Xavi is also an attacking midfielder...which was my point when comparing Xavi and Xabi you're talking about attacking and if anything defensive. Xabi's role for Spain is as a back-up so Senna really, he's a deep-lying playmaker. Fabregas is a more typical central midfielder that does a bit of everything and both Iniesta and Xavi are very much attacking midfielders. My point on Iniesta stand though, arguably the best player in the world at the minute (or atleast until his injury). Xavi's game is as an advanced playmaker, he rarely ever loses the ball...his stats are incredible. Iniesta isn't too dissimilar however makes more runs into the box.