For what it's worth it, since you also mentioned populism, a 2018 study abstract:
A comparative content analysis of nine thousand stories from fifty-nine news outlets in ten European countries shows that both media factors (e.g., tabloid orientation) and political factors (e.g., response of mainstream parties) influence the extent and nature of populism in the media. Although newspapers in most countries do not overrepresent populist actors and tend to evaluate them negatively, we still find abundant populist content in the news. Several media outlets like to present themselves as mouthpieces of the people while, at the same time, cover politicians and parties with antiinstitutional undertones.
Skimming the paper, their list of populist parties comes from previous papers:
we rely on previous lists proposed by Mudde (2007), van Kessel (2015), and
Rooduijn et al. (2014) to identify populist actors. We consider an actor to be populist if they are affiliated to a party which at least two of these authors listed as populist parties.
- Mudde, Cas. 2007. Populist Radical Right Parties in Europe. Cambridge University Press.
- Rooduijn, Matthijs, Sarah L. de Lange, and Wouter van der Brug. 2014. “A Populist Zeitgeist? Programmatic Contagion by Populist Parties in Western Europe.” Party Politics 20 (4):563–75. doi:10.1177/1354068811436065.
- van Kessel, Stijn. 2015. Populist Parties in Europe: Agents of Discontent? Palgrave Macmillan
The 2018 paper itself doesn't contain a full list, but it does have this table, which is indicative; of note they include some (populist) left-wing parties as well:
And their analysis:
Table 3 shows the voter turnout of
right-wing and left-wing populist parties and contrasts it with the frequency with
which these parties have an opportunity to speak on the right-wing issue of migration
and the left-wing issue of labor market policy. The percentage was calculated based on the total number of statements made by all political actors on each issue.
As the results in Table 3 indicate, the hypothesis was not confirmed over all countries and issues. Only in Italy, the Netherlands, and the United Kingdom, we found the right-wing populist parties to be significantly overrepresented in stories about immigration. For
most populist parties, however, we found a strong underrepresentation in news on their owned issues.
our results suggest that in
countries where populist parties are excluded from any form of cross-party cooperation
(Germany, France, Netherlands, and Sweden), journalists restrict the visibility of
populist actors further than in other countries (Table 3). A test for group differences
found that the average overrepresentation of populist parties is lower in systems with
cordon sanitaire (+11.2 percent) than in those without (+19.3 percent); however, the
high in-group variance and low number of cases prevent this difference from being
statistically significant—T(14) = 0.08; ns.
(Frankly, a study like this is bound to be methodologically debatable, at least in corner cases. For instance, in that table, UKIP is scored on their national election vote share rather than EP election results, on which they did much better in the same timeframe.)
They also do a quantitative tone/sentiment analysis on the stories, which is far too long to detail here, but the authors' overall conclusions on that
most news outlets actively oppose populist actors. Members of populist parties are evaluated more negatively than other politicians and are actively challenged by journalists in their stories [...]
The most negative
tone toward populist actors was found in the Netherlands [...] ,
and Sweden [...], which have an effective cordon sanitaire. Only in
Austria, [...], and Bulgaria, [...], where populist
parties have been part of the government, the tone toward populist actors was not significantly
negative and was even slightly better than the tone toward other politicians.
The cordon sanitaire explains 36.5 percent of the variance of tone toward populist
actors, [...], in our sample. In conclusion, the representation
of populist actors and their evaluation is lower in countries with a political cordon sanitaire.
As for the effect of the newspaper type, there were no surprises:
populist tendencies are stronger
for tabloid than broadsheet newspapers—not only with regard to the initiator but also
the gatekeeping and interpretive role—is in alignment with previous research and
theory (Krämer 2014; Mazzoleni 2008; Moffitt 2016). Although cordon sanitaire is the
most important political predictor, tabloid orientation is the most important media
predictor for the extent and nature of populism in news.
A 2016 review about "Far Right Parties in Europe" doesn't alas point to any similar paper that would more directly answer your question on the far-right coverage, although it does have a section on the media, which cites various papers stating position principles on how the media should cover such parties and a few papers (mostly on the Dutch media) that discuss the difficulty of separating e.g. the topical discussion on immigration from the increase in popularity of such parties.