Three Top Class Midfielders Linked & Man United Must Sign?

Manchester United are still in search of a top quality midfield signing to further reinforce the department for next season.
As per the reports going on in the media, there are three top quality midfielders linked with a move to Old Trafford. The players in discussion are Schweinsteiger, Schneiderlin and Gundogan.
The question is, who is the best of the trio? Who must Man United sign?
Schweni remains one of the best CMs in the world. Brilliant passer and striker of the ball and has been pivotal for Bayern over the years. Arguably one of the best stars of the 2014 World Cup as well.
Can play as an effective deep lying playmaker and creative central midfield star. However, he is 30 years old, slower than the other two stars.
Schneiderlin has been brilliant for Southampton in the past two seasons. Biggest plus, he is a PL proven player, a strong defensive midfielder, not better than Ilkay or Bastian as CM.
Not to forget, United already have an established central midfield star in the form of Ander Herrera who signed for Red Devils last summer from Bilbao.
Gundogan is arguably the most complete midfield star among the three.
Capable of playing as a defensive midfielder, deep lying playmaker, creative central midfielder and attacking midfielder as well.
The Dortmund star had major injury concern last season but has bounced back well since returning.
In your Opinion, which midfielder must Man United sign?
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