[Pauloxxi]

None of them. BMW CPO in service since end of 2014, you have almost no warranty time remaining, although the price seems low, it also crashed per Carfax.
Being a 2015 (built in 2014) you may also be subject to time chain issue.

I don't know enough about Mercedes, although you are comparing completely different styles, a more classic Mercedes and a BMW with sport package.
this Mercedes seems too expensive and you need to pay extra for additional warranty.

I think for the Mercedes price you could get 2017 or 2018 BMW CPO with remaining 2 or even 3 years of warranty... for these reasons I would keep searching.

Just my $0.02, since you asked.