Deciding between two higher milage Audi's - Advice appreciated!!

Hello,

I am currently in the process of checking out these two vehicles:

A 2006 A6 4.2 w/ ~185km

2006 Audi A6 4.2 quattro , https://www.kijiji.ca/v-cars-trucks/calgary/2006-audi-a6-4-2-quattro/1345319777?utm_source=com.google.android.apps.docs&utm_medium=social&utm_campaign=socialbuttonsVIP&utm_content=app_android

And a 2004 A4 Avant 3.0 w/ ~225km

2004 Audi A4 3.0L V6 AWD, https://www.kijiji.ca/v-cars-trucks/calgary/2004-audi-a4-3-0l-v6-awd/1326377400?utm_source=com.google.android.apps.docs&utm_medium=social&utm_campaign=socialbuttonsVIP&utm_content=app_android

I would prefer the A6 for the size and power but I'm worried about reliability of the 4.2 engine and higher maintenance costs of the A6 in general.

I know the 3.0 engine is one people warn to stay away from, but they're offering 6mo warranty included, with the option to extend for 6mo or 1yr for $500 or $800 respectively. I was informed the warranty covers engine, transmission, seals, gaskets, and diffs.

What are people's opinions on these vehicles? The A6 not having pictures up yet makes it harder to say, I know, but I'm going to see it tonight so I could update with some photos if required.

Thank you in advance to anyone who responds.