There really is no competition for Keyshot when it comes to ease of use and quality, especially for product shots, but I believe Keyshot is lacking compared to Corona or Vray with respect to interior rendering; GI, noise reduction, fireflies, and displacement are a few grievances in that area. However, Keyshot's material editor, HDRI editor (!), and camera system are extremely powerful - other renderers should take note.
Thanks for sharing feedback!
We're addressing displacement mapping and some features related to interior rendering at the moment. :)
Can you elaborate on any of the details regarding interior rendering?