I came here to say him, and I'm surprised you were the only one who mentioned him!
Falcao was a great striker, but it's fair to say he was bad for us. Understandable, considering he was recovering from that ACL injury, but a shame because he did return to fantastic form a couple of seasons later. He scored over(?) 30 goals again, and put in great performances like this one away to City in the 16/17 season:
That Falcao alongside a motivated Di María is what we were all dreaming of back in 2014. Regardless, he always gave 100% and came off as a very likable guy. It's why he got such a great reception when Rayo Vallecano came to Old Trafford for a friendly a couple of years ago, and he still thinks fondly of us despite struggling here unlike Di María.