I think that that depends a bit on which version of Windows you want to look like and how many shell extensions you’re comfortable with.
I suspect that the OP’s system would be fine with either. Personally, I tend toward XFCE on low-end systems because as it expects less of the GPU/compositor.
Absolutely +1ing XFCE here for older hardware.
I also agree that KDE would be a nice choice too as it performs significantly better than it used to (~750mb ram nowadays)
If you want to make it look as much like windows as possible you can install Zorinmenulite on XFCE from the AUR (I also made a fork for Manjaro-related stuff back when I was still on manjaro)