A veteran of 94 Grand Prix starts, Montoya clinched seven victories between 2001 and 2006, four with Williams and three with McLaren, before heading to the US, racing in NASCAR and more recently in Indycar.
In an interview with Formula 1's official website, asked which drivers pushed him during his spell at the pinnacle of motorsport, Montoya offered an interesting assessment.
"I think all of them," the Colombian said.
"I learned a lot when I ran with Ralf (Schumacher), he was really quick. But European drivers are very weak mentally.
"You can get in their head really easily and I think that explains what you're seeing today and what you've always seen in F1.
"When things go their way, they're really strong. When Lewis is winning, he's unstoppable but if something goes wrong, they spiral down, it's huge.
"If the cars' were closer together I think you would see different people winning."
Montoya, whose 'weakness' in 2006 prompted McLaren to part ways with the Colombian mid-season, conceded however that Michael Schumacher was as tough as they came.
"Michael was one of the few guys that was really strong. You could get in his head but he was strong.
"Ralf on the other hand was a guy who was nearly impossible to beat, but if you could beat him on his A day, you could get in his head.
"We all have our weaknesses, you just got to figure out which ones they are."
"Vettel is probably one of the most complete guys, and also Fernando, I ran with him in my career. I think those are the two best drivers overall.
"Lewis does a really good job but he's in the best car. It's very easy to think that a guy in the best car is the best driver.
"But the question is, if they were not in the best car how would they handle things. Fernando and Sebastian have endured that and I think they are the best."