To my surprise, I've found myself shooting more and more with the TTArtisan 27mm f/2.8 AF pancake lens. I got it as my first lens on the system as it was cheap and I wanted to futz around a bit before deciding on what kind of expensive lens to splash out on.
But this one... I like. its imperfections make it ideal for film recipes. Darkening at the corners adds to that 'old lens' feel, even though it's new. And the swirly bokeh has an almost Helios quality.
On an APS-C camera, this 27mm has coverage making it more or less a 40mm, and to my surprise I have found I think I like that coverage more than the 35mm I used to use a lot with my other camera(s). It's a nice half way between the 50mm and 35mm options which are so common.