I haven't lived in the countries in question, so I don't have any personal experience to go on. The only measures I have are the various indexes of quality of life and other academic studies. According those we have the following rankings:

Economist Quality of life index (2005):
Switzerland: 2
Norway: 3
Sweden: 5
Iceland: 7
Denmark: 9
Finland: 12
US: 13

UN Human Development Index (2007):
Iceland: 1
Norway: 2
Sweden: 6
Switzerland: 7
Finland: 11
US: 12
Denmark:14

All of these countries are quite rich by international standards, but their GDP per capita at PPP varies from a low of 29,650 in Sweden to a high of 41,529 in the US. The Nordic countries do better in their quality of life rank than their GDP per capita PPP rank, and the US does worse, (as does Canada, my home country, at least in the Economist survey). So all of these countries are doing just fine economically, whether they have oil reserves or not, and being rich certainly helps with 'quality of life' but it isn't the whole story.

What matters much more than a quality of life index or a measure of economic strength is happiness. This is a much tricker question, since it is subjective, culturally dependent, and personal. Historically happiness has been disregarded as an area for academic research, but over the past few years that has changed. The studies are still in their infancy, but what they tell us now is that different cultures value different things for their happiness (wow, shock, I know) such as personal success in the US, and family ties in Japan. The other finding I know of, which I find more surprising, is that trust seems to be the most important element in happiness.

I apologize for the lack of a link in advance, this is based on memory of a talk I attended last year. In a study done by a UBC researcher in Canada, based on census data and surveys done across the country, researchers measured interpersonal trust on a ten point scale, and recorded other factors such as wealth, relative wealth, personal safety, and so on. They found that a one point increase on the ten point scale in personal trust in your boss at work had a larger impact on happiness than doubling your salary.

They also found that trust in your neighbors was essential to happiness. Here the results get more interesting, because things that provided trust in neighbors was basically length of time you'd been neighbors, and speaking the same language. Any location facing rapid growth by in-migration has a risk in happiness and trust, and if that growth is international immigration by people who don't speak the same language trust is further at risk, as is happiness. If these results generalize beyond Canada, which they might not, I would expect countries which are rich, non-corrupt, and stable in their cultural composition to be happiest, which makes Iceland a good candidate for a high rank.

Regardless of the overall happiness of a country, moving there if you speak a different language, and value different things, is unlikely to make you or anyone else happy, at least in the short term. So wherever your personal values match up with local conditions, given a certain baseline of wealth and security, is likely to be the best place for you and just as likely to not be the best place for me regardless of any particular ranking.