Midfield
Left Wing

This is one of the more straight-forward inclusions in the list. Giggs made the left-wing spot his own for nearly 20 years and even became the club's all-time appearance record holder, making nearly 1000 appearances and scoring over 150 goals.
Giggs is a living legend and many expect him to return to manage United one day (he did have a brief stint in charge in 2014 after David Moyes had been sacked).
Central Midfield

Again Scholes' name speaks for itself. Widely heralded as the most gifted Englsh midfielder of his generation, if not all time, Scholes' unassming attitude belied a serious technical ability not normally associated with English players. Though his goalscoring rate declined in the later stages of his career, he was capable of executing a defence-splitting pass right up until his retirement. Many, myself included, think he retired too soon.
Central Midfield

Maybe we'll only truly appreciate Michael Carrick's ability when he retires at the end of the season. The Geordie has pulled the strings in the Man Utd midfield for over a decade now and will be sorey missed. In his early career Carrick was criticised for only playing well when Scholes played alongside him. However, since Scholes retired, he has arguably been Man Utd's best performer, along with David De Gea.
Right Wing

The combative Ecuadorian has been at United for 9 years now and is a personal favourite of mine. Perhaps he is one of the more controversial players on this list, but his adaptability merits inclusion in itself.
Though he spent the early part of his career as a rampaging winger (with Sir Alex strongly denying his prospects as a replacement for Ronaldo), his successful conversion to attacking full-back has been impressive. If anything, Valencia is playing better than ever and continues to chip in with some important goals, often spectacularly.