Poyet, who also played for Tottenham Hotspur and now manages League One leaders Brighton and Hove Albion, said the football being served up by England's top clubs this season lagged behind what was on offer in Spain.
"I'm a bit critical of the Premier League this year," the Uruguayan told Reuters by telephone when asked for his views on an intriguing title race that still has five teams involved.
"I know people may not agree with me but I don't think it's one of the best Premier Leagues in the last few years - to be honest I think it's one of the worst.
"Maybe it's more competitive and interesting but at the same time I would say there is not one team that is really better than the rest. Some say the other teams are getting better but in my opinion the top teams this year have got worse."
United, two points clear with games in hand on all their rivals before Sunday's trip to fourth-placed Tottenham, can emulate Arsenal's 2003/04 Invincibles, having suffered no defeats in 20 league games.
Poyet, however, said the Old Trafford team were simply the best of a sub-standard bunch.
"Look at United, they are not even playing well but they are top. They deserve to be top, don't get me wrong, but if they are top without being at their best what's happened to the rest?
"Look at any other league. If you go to Spain, Barcelona are top because they are absolutely fantastic. If you go to Italy, the same, the teams that are top there it's because they are doing so well and playing good football."
Poyet said some of the matches between the leading clubs in England had been poor.
"I've been very disappointed," he said. "Apart from Arsenal v Chelsea, all the rest including the Manchester derbies and Arsenal v Manchester City, were awful.
"You expect more but it's even difficult to pick the best player in England. The Premier League has to be careful.
"I think the best players in the world give you something every week to be happy about. In Spain you watch Barcelona and Real Madrid every week and (Lionel) Messi and (Cristiano) Ronaldo are always, always giving something," added Poyet.
"The fans will think the money they paid for their ticket was worth it. If I go to Manchester every week it's difficult to pick a player... the same at Chelsea, and I could go on.
"Only (left winger) Gareth Bale at Spurs has been exceptional."
Poyet believes fifth-placed Chelsea, despite their debilitating loss of form since setting a searing early pace, are capable of catching United despite being nine points adrift.
"I hope after the 7-0 (FA Cup) win over Ipswich (on Sunday) everything will go back to normal and they will go back to what they were doing at the start of the season," said the Uruguayan.
"They can come back and win the title, no doubt."
