Moyes, who signed Mohammed Kudus as West Ham manager, admits he sees the Ghana international's move to Spurs as the best piece of transfer business this past summer.
Ahead of Everton's clash with Tottenham, Moyes said: "He's a brilliant player. He has so many attributes to his game. He is a great boy to work with. I hugely enjoyed managing him. I had a good relationship with him.
"He has great strength, great balance, can't knock him off the ball. He can play inside or outside, he can play several positions if you want him. He is just finding his form at Tottenham. I see him doing lots of things whether that is scoring or creating goals.
"At the moment, from a distance, he looks like their best buy of the summer. I am not a Tottenham expert but that's how it looks."