MySQL is so incredibly popular. At least, that's what the internet says. When I was job-hunting I was hard-pressed to find something that wasn't a database-less Java programming job or working with MSSQL (blech).
Regardless, almost every project I've worked on or job I've had has required me to interact with and manage a MySQL database (or MariaDB, if you prefer). When tasked with creating a table, adding a fulltext index, modifying a view, or even adding a trigger, using a GUI is preferable to wrangling the commands straight from the mysql prompt. If you aren't a MySQL wizard, then you need to have some visual feedback for what you're doing.
There's no shortage of MySQL GUI programs. I personally used PHPMyAdmin for many years, but when I started working with larger data sets and more complicated queries I found it to be a bit cumbersome and at times very slow. I then used the good ol' MySQL Workbench from Oracle. This does the job and does it well-enough. But I always found it buggy, prone to crashing, and just overall unpleasant.
Recently though, I switched to using HeidiSQL and I'm never looking back.
This program is as straightforward and beautiful as it gets. You set up your connections and get going. You can have multiple sessions going at the same time in the same window and can touch virtually every aspect of your database (I've yet to come across something I couldn't modify with this program). At the bottom of your session window is the output panel, where every single SQL command gets displayed so you know exactly what you're doing.
Let's talk about UI. Everything is incredibly intuitive. From adding rows, to creating indices, to managing your users. Everything just makes sense. You can dump data from any result set into a variety of formats and can even dump a database into another database you've set up in your connections tab.
It's also very fast. I dumped a 10gb database between two servers in the span of an hour without a single error (and that's from a 10-year old MySQL install to a brand new MariaDB!).
Also, it's not just for MySQL. MSSQL, MariaDB, and PostgreSQL are all supported. How about that? Go ahead, try and transfer data between two different database types. Yep. It works.
With this in your toolbox, you can't go wrong. It's become an indispensable part of my development process and I don't foresee ever using anything else. The program is developed primarily by one Ansgar Becker. How do all of these amazing programs exist at the hands of (mainly) one developer? I never have the time. But in any case, after you've downloaded it and had your mind sufficiently blown, you can donate to Ansgar and help him continue the great work on this excellent tool.