It's possible that we just had a unique education experience. And yes, I've been listening to a lot of Hamilton.
I'd say it's down to two big factors.
One is that for various reasons Hamilton's importance as a founding father has been downplayed after his death. Prior to the recent upsurge in interest in his life Hamilton was seen as a small player in the founding of the US, despite his roles in shaping the political landscape and his very important military, political, and philosophical contributions during the early years of the revolution and the nation.
The other is that Madison had a much larger hand in the shaping of the constitution itself, as well as the bill of rights. Additionally, the most important federalist papers tended to be written by Madison, even though Hamilton wrote more of them. For example, Madison wrote Federalist Paper No. 10, which is a very highly regarded piece of political writing overall, and ranks as one of the most important of all the works in the series. And Federalist Paper No. 51, also by Madison, concerns the issue of checks and balances in government, which is an enormously important work, especially so in regards to the constitution.
The Federalist Papers are broken up into several different parts. Some are on general topics, several are on the insufficiency of the articles of confederation, while most are in depth discussions of the particulars of the proposed constitution. Madison's papers cover the "General View of the Powers Conferred by the Constitution" (No. 41, continued through 42 and 43) and outline the house of representatives and the senate (52, 62, et al), while Hamilton's add some additional details and outline the executive and judicial branches.
Arguably Madison's and Hamilton's contributions to the Federalist Papers are roughly equivalent. Both contributed to arguing against the articles of confederation, both contributed basic arguments "from first principles" for the particular form of government proposed, and both explained key parts of the structure of government outlined in the constitution. Madison's authorship of No. 10 and 51 as well as his much greater contribution to the constitution likely tips the balance in his favor.
Two factors:
Madison wrote the most-read of the Federalist Papers, No. 10, which deals with the problem of faction.
Madison is also considered to be the "father of the Constitution" because his notes of the proceedings form much of the basis of our understanding of what the debates were about.
Adding onto this: what are some good books to learn more about Hamilton?