Which OS?

I am no Linux expert. I am completing a PC out of older parts, AMD Phenom II X2, R5 230 1GB graphics, 8GB DDR2 RAM, SSD, USB 3 riser card, and are looking for a suitable OS for it. I have Mint 18.02, previously had Maui 17.06, tried Netrunner 17.10, no Discover. As an alternative for Win 10 I believe Discover is a real plus. Tried Netrunner Rolling 2018.01 and was very impressed. Have just tried Netrunner 18.03 Idolon, also impressive. But as they seem to me to be near identical I wonder why they both exist and which to choose. Any pros and cons for these? Thanks.

Hi Australis,

Debian is more slow changing, but if you enable Testing repo, you also get rolling aka continous updates.
Arch is more fast updating and generally a bit more on the edge, but with Manjaro keeping an ~4 week gap between arch releases and updates that affect Rolling.

One uses apt, the other pacman.

So while both are 100% free community driven bases, the choice is in the details.

Oh, and arch comes with MSM (Manjaro System Managing) tools that are often simpler or extend functionality of the KDE kcms, like the hardware driver kcm or the linux kernel kcm, both which debian lacks.
So keep debian if you want to be more on the safe and slow progressing side and arch if you want/need the latest and greatest (maybe think if you always update every app on your phone to the latest or rather stay on what you like and got used to).

Thanks for that. I am gravitating towards Netrunner Rolling 2018.01. I ran them both off USB keys on my own existing PC but will try them on the other older PC in the next couple of days.