"most favourable light" is correct and usable in written English.
You can use it to refer to a situation or person that is seen in the best possible way. For example, "By sharing our success stories, we can present our company in the most favourable light."
A system in which a lawyer presents a client's case in the most favourable light permitted by law and in which the court must decide the merits of the case may well produce different answers than those produced in a system that assigns a higher priority to the lawyer's duty to the state to assure proper administration of justice.
Scientists certainly make mistakes, and also seek to present their results in the most favourable light, but the scientific peers of an author who review his work for publication cannot be expected to repeat and verify it, so they have to start from the assumption that any manuscript they receive is telling the truth as the author sees it.
"As supporters, we have a duty to represent our club in the most favourable light possible and scenes like those last night fall far short of the mark.
While it is understandable that medical tourism brokers, in an effort to portray their product in the most favourable light possible, may be reluctant to address the issue of risk on their websites, this omission is potentially misleading and unethical.
When asked to review cases from their own institution, clinicians may interpret outcomes in the most favourable or positive light.
A few articles tried to position the mural as something that could be 'haram' or blasphemous for some, [but] most presented the project in a favourable light.
The mass Sony cyber attack has shed some less than favourable light on Hollywood's most senior movie executives.
This is a highly original and provocative view, well worth considering seriously; it also shows Lloyd George and his followers in a more favourable light, and for different reasons, than in most accounts.
We hypothesise that for most of these respondents their choices reflected their desire to present themselves in a favourable light, with social desirability biasness manifested in non-trading behaviour.
In seasonal breeders – animals that successfully mate only during certain times of the year – light plays a part in the regulation of reproduction, to ensure that birth occurs at the most favourable time of the year.
"We were painted in a less favourable light," he says.
