Hay guys, could either of you give me a quick comparison of Kerkythea vs. Vray?

I'm about to spend time getting more in depth with Vray, and wondering if it wouldn't be worth while getting familiar with kerkythea first.. or instead, or both?
This is with exterior arch viz in mind.

Hi, my namez: "NO, Bad Kitteh, NO!"  Whaz yurs?
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