I think the EM1 is a "better" camera, it should be as it is their "pro" model, EM5 is 2nd tier but is newer technology. IF you are into video go with the EM5, if not either or, if your a lens collector and might pickup some older 4/3rds glass ( it is bigger and heavier though) go with EM1, it has phase detect AF on sensor. Both are weather proof freeze proof and very well built magnesium alloy bodies. There are plenty of reviews online to read but ultimately it should come down to ergonomics/fit in your hand. And I would def get the grip just for the extra battery onboard, battery life is not great, 4-6 hours of use. Oh and the EM1 has a panasonic sensor the EM5 has a sony sensor if that matters to you. The other thing I miss on the EM1 is the twist and flip lcd panel, it has a tilt screen only, EM511 has twist & flip.