I was searching for some time the answer to the following question:

What’s the difference between utf8_unicode_ci and utf8_general_ci (MySQL collations)?

I have almost no knowledge in PHP/MySQL, so I have read with the great interest the following info:

http://forums.mysql.com/read.php?103,187048,188748#msg-188748

Generally speaking, it looks like the difference between these two collations is not too big; also, it appears that utf8_unicode_ci is more precise, and utf8_general_ci is faster.

I suppose also that if you plan to write in more than one language and/or to write in a language other than US/UK English, then utf8_unicode_ci is the better choice to make — for example, the German letter “ß” will be correctly sorted near “ss” (this won’t hapen, if you use utf8_general_ci collation). There are other differences, too, so drop a look at the article, if the topic interests you! :-)