Pronunciation of "of"

Is "of" always supposed to be pronounced with the v sound (like "ov")? Or does it depend on the region (e.g. US, UK) or maybe on the word that follows the preposition?

For example, how would you pronounce the title of this question?

Solution 1:

In English (well, OK, UK, US, Australian and NZ English, at least, but I suspect all English), "of" is pronounced with the 'v' sound, as "ov". This helps to distinguish it from "off", a separate word (meaning "not on"), pronounced with the 'f' sound.

Solution 2:

The word of is often pronounced weakly, and the /v/ sound at the end of of is sometimes pronounced as [f]. The phrase “of course” is a typical example. I think that the /v/ in the word of is often pronounced as [f] before an unvoiced consonant.

Honestly speaking, this came as a surprise to me. As a foreign speaker, I learned the following “rule” at school: the word of in the phrase of course is pronounced with the “f” sound. (A similar “rule” is that the word have in have to is pronounced with the “f” sound.) Learning it as a rule had given me a (wrong) impression that English speakers are aware of it. However, while looking for a material to back up this “rule,” I learned that this is merely a variation of the actual sound of the same phoneme /v/.