HenKiIt depends.
Both:
+ Ibis (edit: actually the Sony a6000 may not have ibis)
+ Both are mirrorless, allowing compact camera sizes
- Both are cropped sensors
The E5MII
+ Bigger lens collection do to overall maturity of M43 system and the open nature of the mount
+ Cheaper lens options
+ Lenses are smaller because of smaller sensor, this a 3 or 4 lens travel kit will weigh less
+ Lots of knobs and customization
+ Some lenses also have lens stabilization
- Their native raw file was originally difficult to deal with, less of a problem now though
- High learning curve and poor support
- Smaller sensor size, meaning poorer low-light performance and less depth of field
- Olympus is less known/prevalent - less third party options for things such as battery grips
Sony a6000
+ Bigger sensor size = better low-light performance and better bokeh + depth of field
+ Better third-party brand support for accessories
+ Lower learning curve to use
+ Generally better image quality over M43
- Lens selection still a bit limited
- Lens are generally more expensive
- Not many mechanical settings buttons or knobs
- Reviews often point to the hard menus to navigate
- Not sure what direction of this sensor in their line-up, with Sony's increased investment in their new Full Frame mirrorless line