Other than importing data, why do you need a GUI tool at all? I've used PostgreSQL for fifteen years and managed everything I needed to do by entering SQL commands with the psql client. It forced me to learn about the intricacies of SQL syntax and become a more competent database administrator as a result.
When I started using PostgreSQL, MySQL was not available under a license that permitted free redistribution. As somone who was building servers for clients, that was a major obstacle. I started using PostgreSQL and never looked back. While MySQL was shuffled around among a variety of corporate owners, I just continued to use the one database I knew would always be well-supported and unencumbered, PostgreSQL. I've never regretted this decision.
Every time I have to deal with MySQL, I wonder why it is so popular. Even the simple task of creating and managing users is much more difficult with MySQL.
If you really must use a GUI tool, I prefer Microsoft Access with the PostgreSQL ODBC connector. I've tried OO Base a couple of times, but it still seems rather clunky.