Differences between Mingw-w64 and TDM-GCC for a simple GDI project

Question

I need to build a simple non-commercial tool (dealing with Windows GDI API) on Win64 for Win64 (no cross compilation). MinGW seems the best option for me.
I have already

Answer 1

I've posted a short overview of MinGW / MinGW-w64 / TDM-GCC here: What is the difference between Orwell's MinGW and TDM Dev-C++ versions?

Which is the equivalent now?

It seems, there's no MinGW-W64 version of mingw-get; not sure if this is still valid. However, MinGW-w64 contains a nice installer.

Btw. MinGW-w64 is not just a "64 Bit port of MinGW" - it's more.