I for one definitely would recommend Mint. Ubuntu has a weird GUI (unity). Both of Mint's are far better (they do have KDE if you prefer it though).
Unity's not bad, especially if you have never used another distro before. Once you're used to it, it's very fluid, and I find things more easily than I did in GNOME Classic.
Besides, Unity is just the front-end. You can install GNOME Classic instead if you don't like it.
Mint's GUI is definitely nice, though, I agree there.
which edition of mint should i get?? mate?? cinnamon?? kde?? xfce??
Mate is probably the most stable and is largely standard for Mint. Cinnamon is a newer interface that came out last year, so it is a bit less stable but you might like the appearance better. KDE I haven't used before so I can't comment. XFCE is relatively minimalistic compared to the first two, and also a bit more advanced.
If you're a beginner and have no idea at all which is best, go with Mate.
Also, 32-bit is recommended because it's more stable than 64-bit. The only limitation on memory is that you can only allocate up to 4GB of memory per process, rather than being limited to 4GB altogether, because Linux is not as stupid as Windows for that.