Which European country is most likely to offer an American citizen asylum? [closed]

From your list, Germany would certainly come before France as a close US ally, yet it is very by-the-book and would still process such an application. Politics might certainly play a role at the end of the day but there is for example a famous recent case of a US citizen seeking refugee status there. Every decision until now has been negative but he is still going through the appeal process, it's not like the interior ministry would put him back in a plane or summarily deny the application merely because he is a US citizen. I know there have been a bunch of cases like that in the UK and Sweden too but I don't recall anyone being successful in recent years.

Generally speaking, the rules do not discriminate between nationalities at all, each claim has to be judged on the merits. The closest you will find to a nationality-of-origin standard is the notion of a “safe country of origin” (this exists in German law for example) but these lists are typically very short and limited to countries in the Balkan that have seen trouble in the past. So you won't find any clear-cut rule about US citizens. And there are so few cases that statistics are essentially meaningless.

Beyond that, Australian example notwithstanding, the situation you described does not seem to match the international definition of a refugee very well and it would therefore seem extremely unlikely to see such a claim accepted.

Seems I am wrong
See what was written in the comments by @user568458:

You'd be surprised, there are a small number of US citizens granted asylum in EU countries every year and it's not a big deal diplomatically. Has been true for years. This WP article has a good summary and quotes a good stat: "12 U.S. citizens were granted asylum in Britain in 2015, meaning about 1 in 5 applications were successful"...

...generally the asylum application experience is different for people from countries like the US because they usually have a valid (temporary) visa already, speak English, etc, plus it's relatively rare, so generally those of us who volunteer at centres, outreach programmes, detention centres etc almost never encounter them (I never did when I used to volunteer). But they do exist

My original answer
Non of the European Union countries.

They will expect the USA to be able to protect its own citizens, and as such asylum will not be granted. Asylum is not easily given, not even to citizens of countries where the government is the reason the citizen has to flee for his life.

They might be willing to give grant to reside more easily than they would for other applicants, but that will be the officers to decide, not the system granting it as a rule.

You can try Russia, as it has proven to be willing to allow USA citizens unwilling to stay in the USA.