The 18-55 is very good for a so-called kit lens, with only some minor weakness at the long end. But I got into Fuji from the 35mm 1.4 as my only lens, which is a brilliant choice overall (despite being noisy) and having only one prime definitely changes your photographic view. The 35/2 is more modern and faster in focusing, but you lose a stop of light and the distortion is higher (but digitally corrected in camera). Would be the alternative if you need weather resistance and quick focusing more than highest apertures.
Whatever you choose, you can't go wrong. I'm a fan of high aperture and low light, so it was obvious for me to start with the 35mm.