While no one can say how Massa views the situation, It has been a long time since he raced against Michael.
The thing with these things is that time allows people to view things slightly differently and what was once viewed a certain way tends to diminish or change over time, but only in our minds. While Alonso & Hamilton are certainly among the greatest elite drivers ever, against a prime Schumacher they'd have a difficult time looking as supreme as they do and quite frankly, I don't know that they could beat him. Both Alonso and Hamilton are able to driver tenths faster than teammates whereas with Michael it was an almost Secretariat-like distance to his teammates and he had a few that were highly regarded in their own right.
To place Verstappen into the top 5 when he raced against a young, as well as a prime Kimi who was as good as the rest of the guys on his list is indicative as to what I'm talking about. Fisichella beat him pretty handily when they were teammates on pure pace but I imagine one season against him as a rookie isn't enough to go off of in order to judge or rate him in this list?
Either way that's a good list but I think it's a bit premature to list Verstappen with all the quality drivers he's raced against. I'm also surprised he didn't list his good friend Ricciardo, but I guess listing his teammate is telling about how he rates them both?