"I think ..." or "In my opinion..." or "From my point of view..."

If I want to express my opinion about something, what's the most correct form? What are the differences? What is more formal and what more colloquial? For example, in Italian, nobody says In my opinion..., but My opinion is...

Solution 1:

As FumbleFingers commented, none of I think … or In my opinion… or From my point of view… is as formal as In the opinion of the author. That aside, I think you have them listed in very-slightly-increasing order of formality.

More important than any differences in formality are differences in nuance and meaning. I think … may be seen as lighter-weight, more off-the-cuff, than In my opinion…, while From my point of view… may be seen as introducing a personal viewpoint or preference, possibly less objective than for either of the other phrases.

If you seek less formal expressions, consider It seems to me …, It appears that …, Apparently, …, Evidently, …, It sure looks like …. But of course for formal phrasing, rather than I think plus a conclusion, instead give a supporting argument or reason, followed by the word hence, followed by a conclusion.

Solution 2:

All three are normal English constructions. Of the three, I think is probably the least formal.