IPA is the best choice for pronunciation transcription. IPA has a long history of development (since 1886) and represents best scientific practice. This means the system is concise, unambiguous and accepted word wide.
Currently IPA is maintained by International Phonetic Association and described in book Handbook of the IPA.
Unfortunately quality of linguistic sources differ across publisher and teachers. You can see in typical dictionary:
But it is hard for non-professional to read dialectic variants:
[ˈɫɪɾɫ] - General American
[ˈlɪʔo] - Cockney
[ˈɫɪːɫ] - Southern US English
Many important dictionary publishers switched to IPA but unfortunately they use wrong IPA transcription just to obey tradition.
For example modern English has
[ɹ̠] (LATIN SMALL LETTER TURNED R) but that sign can scare readers and dictionary publishers often use
[r] (LATIN SMALL LETTER R). Compare sound fragments from:
Another example is dark l (velarized alveolar lateral approximant).
feel is not the same as in
lamp and some English learners may have a hard time to distinguish them:
lamp [læmp] ⇔ feel [fiːɫ]
On the other hand I don't see in popular English dictionaries usage of
ɫ sign (LATIN SMALL LETTER L WITH MIDDLE TILDE).
I see growing practice to use IPA for person or organization name pronunciation (on home pages, Wikipedia, etc) to avoid ambiguity.
For entering IPA into text I uses Emacs X-SAMPA input method and it works great (I build dictionary with it) but unfortunately I don't know any other convenient way to input Unocode IPA sympols.
we have a lot of systems that cover specific langauges or groups of languages. Their main advantage is usually the fact that they are adapted to these languages, and are therefore easier to read. Moreover, they are usually clearly phonemic - they express only contrasts that are perceivable by native speakers of a particular language
It is very true. For example American Heritage Dictionary of the English Language is typically for American dictionaries extensively uses diacritic sign and this system looks like a garbage for me but widespread in USA ((
Examples of inconsistency for pronunciation transcription for English language can be explored here: https://en.wikipedia.org/wiki/Pronunciation_respelling_for_English