BMW 6 Series 2006 or from 2008?

I think the topic was already there, but I can’t find any contribution to it. I’m thinking about getting a BMW 650 convertible. And this was the second model. My question is now, what is more meaningful or enough? A 650 Bj 2006,2.Hand with 150,000km for almost 16,000€ or one from 2008 with 112.000km, 3. Hand for 21,000€ ? Both look like I want. What would be more useful?