!rant
Going to install a Linux distro on my Mac for general dev antics (NodeJS & Java)...

But which one?

Are you asking which distro you should install? I recommend Linux Mint: Cinnamon

@Bobj2008 or ubuntu

@Bobj2008 Yes, and Mint seems like a good choice.
@linuxer4fun Also a good shout, but seems like that's the default choice - are there any drawbacks of Ubuntu?

@code maybe.
When I installed ubuntu on my 2015 macbook pro, it didn't always sleep, so would get hot in my bag, and go flat,
I don't know if other distros would be better, or if there was a fix I doesn't find, in the ends I went back to osx, with parallels with ubuntu, debian, suse ;-)

@code I used Ubuntu and I thought it was slow and hard to use.

@ThomasRedstone what a pain :/ running through a VM is probably a sensible way to get started anyway.

Or I could be a badass and try Kali...

My favorite VM is Oracle's VirtualBox.

@Bobj2008 my main pull is that I want a lightweight OS to play around with, so this is useful advice - thanks!

@code I recommend the Xfce version for lightweight Linux Mint.

Honestly, it really doesn't matter. But if it's your first time installing Linux: trust me, save yourself some pain and go with some flavour of Ubuntu. If you don't like the default desktop environment, Unity (which I hated when it first came out, even though I now use it every day), there are official Ubuntu flavours for most other desktops. Xubuntu is probably worth a look if you're after something lightweight.

I use Ubuntu with heavy customisations.

It is the best bet for plug and play plus you get packaged Deb files if you like that thing (although I used that for Spotify, VirtualBox and chrome. Everything else comes from apt). Mint is also a great option. As is arch :P

Arch is extremely lightweight and teaches you a lot about Linux.

You might want to check out Void Linux too.