I dont know enough about nani to rate him but at 20 and with bale behind him, some of the comments on here are valid.
MGP even if he has stopped developing is a class left sided player who would improve that position whilst brining premiership experience and less need to get to speed with the league, perhaps adapt to the club is fair, but thats minor in comparison, it didnt take Chimbonda any time.
1) MGP - best of the 3 as far as I can tell
3) Downing or Nani, you know what your getting with Downing and he's adapted, he would improve us, but will he continue to develop? Is he significantly better or worse than Nani? I cant help thinking the 'next Ronaldo' is an easy tag to give out when the Ronaldo's and Rooneys of the world are exceptionally rare in reality. lets not be fooled by the fact man Utd are interested, after all they do sign duds after all, e.g. Forlan, Veron, Cruyff all of whom could have reasonably been expected to be better than they were.
Additional -I've just been YouTubing Nani, im not getting sucked in by a highlights reel afterall no one ever puts up lowlights to give you balance.
But he does have a very cool goal scoring celebration that makes keano's ols roll over and guns look lame.