What we really need:
Audio pronunciation, useful definitions, different meanings, syllabication, stress marks/nucleus, and best possible information about word classes, function, derivations, inflected forms, transitivity, countable/uncountable or both, usage, varieties, idioms, phrases, collocations, proverbs, synonyms, antonyms, formal/informal speech labels.
We do need reliability and usability on a daily basis. So don´t waste your time.
First:
I´ve got an email from Warren Ediger,
see: http://www.successfulenglish.com . He just wanted to remind me of MSN´s Dictionary, which I´d forgotten. It´s a great site with effective definitions, collocations, word classes, inflected forms, Thesaurus and audio BUT it doesn´t support the International Phonetic Alphabet (IPA), so you need to learn its own phonetic symbols (Or you don´t). I use this dictionary as tool for extensive lookups. But it isn´t an ESL-Dictionary, it is designed for nativ speaker. For example: The limited use of the verb "belong", there is not any comment about the progressive tense restriction. So it depends on your individual level of proficiency.
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Second best:
Cambridge Advanced Learner´s Dictionary
You´ll get word classes, phonetics, inflected forms, collocations and there´s an option for idioms, phrases and American English. You can search with short phrases and idioms as well.
And an useful different version !!
http://dictionary.cambridge.org/
Cambridge International Dictionary of Phrasal Verbs
http://dictionary.cambridge.org/results.asp?dict=P
Cambridge Dictionary of American English
http://dictionary.cambridge.org/results.asp?dict=A
Third place:
Longman Dictionary of Contemporary English
All in one, but limited audio features - nonetheless an effective dictionary.
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Fourth place:
Merriam Webster
You´ll get the pronunciation with audio in a small pop up, inflected forms, partly synonyms and word types.
http://www.merriam-webster.com/dictionary/
Merriam Webster´s Pronunciation Dictionary with Audio:
http://www.learnersdictionary.com
____________________________________________________Merriam Webster´s Pronunciation Dictionary with Audio:
http://www.learnersdictionary.com
Fifth place:
The American Heritage® Dictionary of the English Language
(Their confusing website configuration is not that bad, you´ll get used to it. I like it for deep grammar lookups, you´ll find there everything about the English Language. Go there, give it a shot !, improve your English)
Sixt place:
THE FREE DICTIONARY (IDIOMS)
Do some lookups for idioms, it´s THE Idiom Dictionary. It is compiled from the Cambridge International Dictionary of Idioms and the Cambridge Dictionary of American Idioms + Thesaurus. ____________________________________________________
Seventh place:
Juxtaposed American and British pronunciation audio files partly available.
E.g. for "Eat"
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Eighth place:
Reference.com All in One. But by far not the best, and they even charge users for getting their audio pronunciation.
