The Dutchman has also stated that Mourinho's side plays 'more boring football' than when he was in charge of the club.
Van Gaal, who was lambasted for his tentative approach while at Old Trafford, says he'd much rather watch Manchester City than United.
"If you ask me how did I do at United, I will say it was my best year ever, given the circumstances I was working under," Van Gaal told the Mirror.
"We played football that was quite alright. But it's not football that is appreciated in England.
"And yet, right now, looking at United, I have to conclude Mourinho is not being criticized while it's far more boring football.
"I would rather watch City play than United. You need quality in a squad and it's clear City have a better squad.
"What United produce now is defensive football. I always played attacking football. The proof is that the opposition were always parking the bus.
"They don't do that now because Jose Mourinho plays so defensive."