I own both. I never carry the Peanut. I have a 6318 in my pocket right now and used it earlier today cutting some pallet shrink wrap, strapping, cardboard, and packing tape on some boxes. Worked like a charm.
Between those two, a 6318 for me. I also like the 63032 version of the Case medium stockman.
It's all about size versus function. The Peanut is a fine knife. But the way I carry mine, vertically in my back pocket beside my wallet, a longer knife works better. A Peanut would fall down to the bottom more easily. So I prefer something in the 3 1/2" to 3 3/4" range. I also like the versatility in the blade types better. I really prefer the regular clip in the '032 over the California clip in the '18, but the rounded bolsters of the '18 make for a slightly more comfortable carry.
Here's the one I usually carry, and that I am carrying now. Pocket Worn Harvest Orange in stainless steel.