McTominay played another starring role in United's Carabao Cup win over Chelsea on Wednesday.
And Brown feels the 22-year-old is only going to improve further.
“He's a good passer, a big tall lad and a good runner," Brown said. "He has definitely been one of the best players, along with Aaron Wan-Bissaka, and you want him playing every week at the moment.
“He hasn't failed at anything, if anything he has excelled and with him being a young lad you can only see him getting better. His attitude is brilliant and he gives it everything."