Who would be the best signing for Manchester United this summer? 

The summer transfer window always sees a host of names being linked with Manchester United. With Fred and Diogo Dalot already announcing that they will be playing football at Old Trafford next year, United will be looking to strengthen their squad further.

Though most of the names being touted will remain consigned to the tabloids and online forums, there are three players who seem to be chronically linked with the red half of Manchester for quite some time now.

Whether or not these rumours will transpire into something more concrete remains to be seen, however even if we were to assume that one these superstars will be a Manchester United player come the 2018-19 season, who would the ideal choice be?

Each of the three players has their advantages and shortcomings, however, they remain 3 of the best attacking players in the world today and would significantly improve the forward line of any club in world football.

That being said, football is played by a team of 11 individuals and for a team to maximise its full potential, the player in question will have to gel with the remaining members of the team. Team chemistry is everything in football, so which of these three players would make the most sense for United to sign?

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#3 Cristiano Ronaldo

Cristiano Ronaldo to Manchester United would be a dream come true for some. But is he the right choice?

The reunion of Cristiano Ronaldo and United is something that has been hoped for, for a while now. While this would be a dream move for many United supporters, one has to remember that every time Ronaldo has said he is unhappy at Real Madrid, he has almost immediately been rewarded with a new contract that includes a wage rise.

Having wrapped up his third successive UEFA Champions League winners medal, Ronaldo is on course for a record-breaking sixth Ballon d'Or and his 15 goals in the competition show that despite being 33 years of age, he is not slowing down anytime soon. One only needs to look at this goal, to dispel any notion that he might be losing his athleticism.

Ronaldo also made his name at United, when he played for the club between 2003 and 2009 and it would be an understatement to say he is Premier League proven. However, his position would be trickier to solve.

Ronaldo has either operated from the left wing or as a striker in recent years, with United having just signed Romelu Lukaku and Alexis Sanchez, would Jose Mourinho and the board be happy to ditch their recent high-profile signings in order to accommodate Ronaldo?

Stranger things have happened in football, but signing Ronaldo at this stage might do more harm for United than good, especially given that this might well be Mourinho's final year at the club given his penchant for cycling through clubs every 3 years.

#2 Antoine Griezmann

Antoine Griezmann almost became a Manchester United player last summer

The one that got away! Antoine Griezmann looked dead set on joining United the previous summer, however with Atletico Madrid having their transfer banned sustained, he opted to stay at the club that brought him to prominence at their time of need.

Griezmann can operate in a variety of positions, having a stronger left foot, he started life out as an inverted right winger before moving to a striker's role for Atletico, while he has also featured as a central attacking midfielder for the French national team.

Of the three, Griezmann remains the only one to not to have played in the Premier League and would represent a bit of gamble, though a player of his ability should not find the rigours of the Premier League too hard to overcome.

Griezmann is also the youngest of the three at 27 years of age and he is also at the prime of his career. Further his rumoured release clause of £89 million would represent extremely good value in today's market.

The primary issue with this transfer would be his playing position in this United team. When United last pursued Griezmann, Mourinho's primary formation was a 4-2-3-1 which would have seen Griezmaan slot in perfectly into the CAM role behind the striker.

United have long since shifted to a 4-3-3 and though Griezmann can play on the right, it would not make full use of his ability.

Further, the signing of Alexis Sanchez pretty much ended speculation of this transfer happening when United gave the Chilean the famous number 7 shirt, which is also Griezmann's preferred number.

With Griezmann already commenting about the fact that he doesn't like British weather and with his good friend - Paul Pogba's Manchester United career also somewhat in limbo, the most likely outcome for Griezmann will be either staying at Atletico Madrid or moving to Barcelona, who are also reportedly interested in the Frenchman.

#1 Gareth Bale

Gareth Bale has previously played in the Premier League while he was at Tottenham Hotspur

Until his wonder goal in this season's UEFA Champions League final, Gareth Bale remained destined to leave the Santiago Bernabeu.

Having been left on the Madrid bench for the majority of the season including in the final against Liverpool, despite being fit, Bale's Madrid career looked finished. When you take into consideration that he is 29 years of age, and is in the prime of his career, Bale should be an automatic starter for any club he plays for.

Coming to a potential move to United, Bale is Premier League proven and his combination of pace and strength seem tailor-made for English football. Bale's primary position is on the right wing which is also a position of concern for United at the moment with Mourinho choosing to play Alexis Sanchez on the left.

The only real issue with Bale is his poor injury record. There is no doubt that a fully fit Bale is a devastating player who can turn the game on its head with a single moment of magic.

However, if he misses large parts of the season through injury it forces the team to look for alternatives in their playing style, something that would not bode well with Mourinho or the team, especially if you're building your team around that player.

However, of the three players mentioned, Bale would represent the best signing for United simply because he is Premier League proven and he would solve United's problem on the right wing.

With a rumoured fee of anywhere between £100 to a £120 million, he still would represent good value in today's inflated transfer market. Whether he would personally consider the move, remains an altogether different proposition.

With Zinedine Zidane leaving the club, Madrid's new manager could possibly build his new team around Bale, given that club president Florentino Perez remains a big fan of the Welshman.

That being said, if United were serious about signing any of the three players mentioned, the additional of Gareth Bale would be the most logical one to make.