I've been using SQLyog for years now. Recently they released v8.0 which includes an updated interface and two very cool features the Query Profiler and SQL Formatter. The formatter was the reason I upgraded this year.
http://www.webyog.com/en/sqlyog_feature_list.php
Blog post with video and animated gif of the SQL Formatter in action
http://www.webyog.com/blog/2009/02/02/profile-and-format-mysql-queries-with-the-new-sqlyog-80/
A few years ago I tried Navicat and the mysql manager but decided on SQLyog. I'm sure both products have been updated since but I'm still happy with SQLyog which is updated regularly.
[Update] - Just downloaded and installed NaviCat 8 for MySQL and was not impressed
After I added this post I reviewed and downloaded v8 of NaviCat for MySQL. In comparison with user interface of SQLyog there is no comparison. SQLyog is better and more intuitive. Especially with the two latest features mentioned earlier. Immediately I noticed how SQLyog keeps you in one window when trying to view the data of a table, while Navicat spawns a new window. The report builder and viewer is the only thing that would put Navicat above SQLyog IMHO, and I already have other means to handle reports using ASP.NET. Try both products and I think you'll agree with me.
