The point of view used when writing a formal academic essay really depends on the essay requirements and the subject you're writing the essay for.
Third person point of view
When I used to write sociological academic essays, the point of view changed occasionally. Talking about research, I'd use third person, as in:
'Zimbardo et al. Conducted the Stanford Prison experiment in 1971.'
Subjective point of view
If I'd go on to discuss the pros and cons of the research, the point of view would become more subjective. Although most essays require you to retain as much objectivity as possible, this is virtually impossible unless discussing facts. This may be possible when writing an academic essay in scientific fields such as chemistry.
Personal point of view
The personal point of view is pretty similar to the subjective, but they can work alongside each other. You'd have to make a judgement on whether it'd be appropriate to use personal experience or anecdotal evidence in an essay, as it could be frowned upon academically. However, in fields such as art history, a personal opinion may be welcomed.
Second person point of view
The second person point of view is rarely used in essays, although using 'you' to mean 'one', may be acceptable. Such as:
'If you were to consider the ethical concerns surrounding Zimbardo's study, you may believe that some of his practices were morally questionable.'
I'd try and stay away from this point of view as it can come across as amateurish.
