A friend of mine just asked me this upon seeing that I had an Olympus E-M10 in hand rather than my more customary Fuji or Sony body. I used to shoot m43 years ago but had moved on to APS-C cameras and not really every looked back. That got me thinking. Why did I choose to to buy another m43 camera? I prefer the image quality of APS-C cameras by a significant margin. I'm not crazy about Olympus colors or JPEGs and I don't like Olympus lenses all that much. So, why the heck did I choose to buy m43 let alone an Olympus camera? Well, I think it boils down to just a few things... I liked the way the E-M10 felt in hand. It fit comfortably and everything was where I wanted it to be. Of course this is something that will be different for each person. For instance I liked the E-M10 and E-M5 but not the E-M10 II. I really like Panasonic lenses. I like how small they are and most of all I like that a number of them can focus reasonably closely. The P20/1.7 focuses down to about 8" and the new P42.5/1.7 focuses to about 10". That's huge for me. I like to get close when I shoot. I know folks LOVE the O45/1.8 and it does have terrific IQ but the minimum focus distance is almost 20" and when I had one that drove me absolutely bonkers. With the P14/2,5, P20/1.7 and P42.5/1.7 I could put together a classic 28, 40, 90 set of focal lengths and all of them would fit into about the same amount of space than as my old Fuji 18-55 (and all close focus to boot). Finally, on the whole m43 gear is pretty affordable, this is due in part to having a lot more bodies and lenses available but no matter what the reason I can manage to indulge my habit on a budget. There are definitely trade-offs but IMHO you get more than you give up.