To have a dictionary of prime and top quality is the first thing to which one should pay careful attention when being a beginner or an advanced learner.

I have tried only two of all online dictionaries so far, as I am content with the dictionary I've been using constantly for 1 year and haven't had any desire to try any other ones since then.

The dictionary that I am referring to is called The Oxford Advanced Learner’s Dic­tionary, which a lot of you are unsurprisingly familiar with, and in my opinion, it is the best monolingual dictionary out.

Link is below:

http://oald8.oxfordlearnersdictionaries.com/ – The Oxford Advanced Learner’s Dic­tionary

I mostly use TheFreeDictio­nary,Urban Dictionary and Macmillan Dictionary.
Otherwise,The Oxford Advanced Learner’s Dic­tionary you present in your opening post does not look bad at all.
Thanks for the tip.

In the last year I've used mainly The Oxford Advanced Learner’s Dic­tionary. In my opinion, it's one of the best online dictionaries.

Owing to the post I have opened recently, I took a closer look at Macmillan Dictionary, and I've found out some information that is quite interesting for me. Macmillan Dictionary is in a sort of way very well arranged, quite extensive in some parts (but it is apparent that every dictionary stands out from others in something and of course lacks the other qualities as well). But in my view, it is very useful for looking up phrasal verbs, as the layout of the phrasal verbs is far better than in Oxford.

I recommend that you try it as well, guys.:)

I suppose you know this article.
I often use all of the dictionaries mentioned there for in some tangled cases it's more than needed. 

For me there are more to consider. When looking up something informal, sort of nasty I usually go for the urbandictionary. In other cases I usually make do with the Macmillan used through Chromes omnibox. I prefer the Macmillan over others, as it has I think superior capabilities when it comes to searching for idioms, collocations and such like. Oh, yeah, not to forget, lately I have been usually etymonline a damn lot. It just makes you understand those deep word meaning interconnections big-time!