Virtualmin is a good panel and also powerful. But the main developer of the *Min group (Mr J. Cameron) is developing everything himself especially in virtualmin. e.g. : 1- Mysql manager of virtualmin/webmin 2- UserMin as a IMAP / POP3 client 3- File manager ( Java )
For managing mysql, phpMyAdmin can be integrated to virtualmin which is more powerful and user-friendly. For email client, there are many popular softwares such as RoundCube, Horde IMP, ... which can be intergrated into virtualmin and they are more userfriendly than Usermin. specially roundcube ... For managing files, the java file manager is good but it is in java. Net2ftp can be integrated as a ftp file manager. I think a non-java file manager is better.