I just look at cost efficiency.
Aquilani ain't coming for cheap. Kenny Daglish knows he can sell him to another club, he'll wait for us to pony up 16m or ship him elsewhere. Daglish is not stupid. Then we have the issue of his wages. 3.5m per annum not including the tax.
Marchisio on the other hand cost us nothing to acquire, is much more versatile, and is on less wages.
I'm not saying Marchi is some kind of all around super consistent beast but lets be objective. Look at what we get from each player and how much it costs the club.
Also, I don't believe Aquilani is as much of a play-maker as some on this board would have people believe. His passing range seems rather limited at times and on top of that his accuracy is pretty bad. Sure if we had a team full of superstars his shortcomings would be masked but we don't, and Aquilani is not what this Juve needs.