Merriam Webster
This
dictionary has ads at both sides of the searching spot/square which makes the
dictionary-site a bit confusing in my opinion. A thing I like about this
dictionary is that it has a button where I as a visitor can listen how to pronounce
the word I looked up. It also has synonyms at the bottom of the site which is a
big plus if you are struggling with a varied vocabulary.
Cambridge dictionaries online
This
dictionary is the most confusing of the tree I chose to use, mainly because it
has too many ads. A funny thing with this dictionary is that it has a button
for pronouncing the word in British English, and in American English. This dictionary
is not to prefer for people in a hurry because of all the ads which makes it
cumbersome.
Heinle`s Newbury House Dictionary

Very well structured and organized presentation of dictionaries. I liked how you illustrated with pictures, made it easy to read as well. Perhaps you could explain the difference between monolingual and bilingual dictionaries?
SvarSlett