[kijinbear]

PostgreSQL forces you to write proper queries. MySQL is designed to accommodate lousy practices, and all those implicit type conversions and non-standard syntax will come back to bite you as a big WTF.

Other reasons I like PostgreSQL: more data types (MySQL doesn't even have a boolean type), partial indexing (a godsend when you have large tables), ability to use multiple indexes when querying, full-text search and ACID are not mutually exclusive, and multiple procedural languages.

[edit] Oops, didn't mean to make this a reply.

[prodigal_erik]

This. I was appalled when I realized that MySQL will quietly seem to execute

  select x from y group by z

x isn't a grouping column or an aggregate function, so where does it get the value for each group? It just arbitrarily picks a value from one of the rows, even if the other rows had different values!