How to decode which version of Golang to install on Mac OS X?

On the official Golang website, in the Get Started section, we read:

> Install the Go tools
>
> If you are upgrading from an older version of Go you must first remove
> the existing version.
>
> Linux, Mac OS X, and FreeBSD tarballs
>
> Download the archive and extract it into /usr/local, creating a Go
> tree in /usr/local/go. For example:
>
> tar -C /usr/local -xzf go$VERSION.$OS-$ARCH.tar.gz
>
> Choose the archive
> file appropriate for your installation. For instance, if you are
> installing Go version 1.2.1 for 64-bit x86 on Linux, the archive you
> want is called go1.2.1.linux-amd64.tar.gz.
>
> (Typically these commands must be run as root or through sudo.)
>
> Add /usr/local/go/bin to the PATH environment variable. You can do
> this by adding this line to your /etc/profile (for a system-wide
> installation) or $HOME/.profile:
>
> export PATH=$PATH:/usr/local/go/bin

When we visit the Downloads section, we are presented with many options:

> go1.4.2
>
> File name Kind OS Arch SHA1 Checksum
>
> go1.4.2.src.tar.gz Source 460caac03379f746c473814a65223397e9c9a2f6
>
> go1.4.2.darwin-386-osx10.6.tar.gz Archive OS X
> 10.6+ 32-bit fb3e6b30f4e1b1be47bbb98d79dd53da8dec24ec
>
> go1.4.2.darwin-386-osx10.8.tar.gz Archive OS X
> 10.8+ 32-bit 65f5610fdb38febd869aeffbd426c83b650bb408
>
> go1.4.2.darwin-386-osx10.6.pkg Installer OS X
> 10.6+ 32-bit 3ed569ce33616d5d36f963e5d7cefb55727c8621
>
> go1.4.2.darwin-386-osx10.8.pkg Installer OS X
> 10.8+ 32-bit 7f3fb2438fa0212febef13749d8d144934bb1c80
>
> go1.4.2.darwin-amd64-osx10.6.tar.gz Archive OS X
> 10.6+ 64-bit 00c3f9a03daff818b2132ac31d57f054925c60e7
>
> go1.4.2.darwin-amd64-osx10.8.tar.gz Archive OS X
> 10.8+ 64-bit 58a04b3eb9853c75319d9076df6f3ac8b7430f7f
>
> go1.4.2.darwin-amd64-osx10.6.pkg Installer OS X
> 10.6+ 64-bit 3fa5455e211a70c0a920abd53cb3093269c5149c
>
> go1.4.2.darwin-amd64-osx10.8.pkg Installer OS X
> 10.8+ 64-bit 8fde619d48864cb1c77ddc2a1aec0b7b20406b38

I run Mac OS X Yosemite, Version 10.10.3, with the following configuration:

• Processor: 2.8 GHz Intel Core i5
• Memory: 8 Go 1600 MHz DDR3
• Graphics: Intel Iris 1536 Mo

Which version of Go should I install?

And most importantly, why (so that I can make a decision for myself in the future)?

You'll want this one:

> go1.4.2.darwin-amd64-osx10.8.pkg Installer OS X 10.8+ 64-bit

Note the key parts: amd64 (64-bit), OS X 10.8+ (of which 10.10.3 satisfies). It's the GUI installer, which automates a lot of the work.

Mac OS X is often referred to as "darwin", which is the name for the low-level OS.