Berbatov draws critics for his languid style but produced a stunning volley to help Fulham record a 1-0 win over Stoke City on Saturday.
Ruiz thinks that Berbatov has looked frustrated at times in his Fulham career because he is determined to get consistent results in West London.
He told Daily Star: "You see sometimes by his body language that he really wants to win. That means he cares.
"He is one of the best players I've played with. I don't remember one player with the same skills as him. We try to look for him as we know he keeps the ball and he can score, like he did in this game.
"It is easy playing with him as you can give him the ball and he will not lose it, and you can also get it back from him. Also, with his movement, he is very smart to play in front of and that makes for a good team player."
The 32-year-old has scored nine Premier League goals for the Cottagers this season.