Simple solution --- get into a camera shop, handle all three, take some sample shots on your own memory cards, and then buy the one that feels the best in your hands. The more you fuss over the choice, the more you are going to be subject to buyer's remorse - and the reality is that there will be a better model introduced to trump what you bought within weeks after your purchase anyway.
All three of your noted cameras are good mid-range units -- and aside from personal preference would work equally well. The lens differences are pretty much moot. Shop around enough and you'll find comparable lenses for either make.
Olympus e-620 / 14-42mm / 40-150mm
Metz 48 AF-1
Kata 3-N-1 20, LowePro Orion Mini, LowePro Nova 2