Sneijder is the better player IMO, with his passing & freekicks especially... A more consistant performer but his little nighling injuries are a concern...
Nasri is a bit inferior but is quicker and better at getting round players, scores a few as well... No injury concerns really but can be a tiny bit inconsistent at times...
Mata is probably the fastest and similar to Nasri, decent goals record from midfeild also, but apart from pace, I'd say Nasri has *slightly* all round better abilities, again all IMO.
Pastore is a passer, has a great brain. He knows where he has to be and is tall, so should suit the prem.
Lavezzi is definitely the quickest... But he's also the one I know least about TBH, he's very tricky. He's 26 and IMO not totally 'World Class' like Sneijer at 26/27.
Nasri, Mata and Pastore are the youngest, and Sneijder the best over all, so my list of preference would be:
1) Nasri/Sneijder/Mata (taking all into consideration, including Sneijders little injuries and Nasri/Matas younger ages, there's no separating them IMO, even though they're slightly different styles of players)
2) Pastore (just, just behind those in 1)
3) Lavezzi (probably change my mind if I saw a bit more of him TBH)