My main browser at one time was Mozilla Suite. It was a browser and email client all in one. Somewhere down the line the Mozilla foundation gave up it's development and it was taken over by another organization and re-branded as SeaMonkey I wasn't sure what to expect so I switched to the Opera browser as my main one but kept using the email client in SeaMonkey.
I still use the SeaMonkey browser occasionally. But one grudge I had against SeaMonkey email, and this has been an issue for a long time now, if you clicked on a link within a email the SeaMonkey browser would open instead of your system default.
I decided to go online and search for a solution this long standing problem. They say it's a bug but I think it's on purpose to promote the browser. Anyway I found an extension called Standalone SeaMonkey Mail at https://addons.mozilla.org/en-US/seamonkey/addon/standalone-seamonkey-mail/ that solves this problem.
It's no secret now that I'm dissatisfied with the way the Opera browser as been developing. I spent time and time again going online mostly to the Opera forum to try and figure out how to customize this or that and finally get it set up to my liking only to have an update screw it all up.
I've experimented with other browsers but ended up coming back to Opera. I would use it as long as I could freeze it at version 28 and disable the automatic updates. Controlling the updates was one of my main grudges with Opera and why I don't use Chrome and have no plans to upgrade to Windows 10. With Windows 10 you have no choice at all.
To keep it at version 28 I deleted the auto-update files in the Opera folders and then deleted the scheduled task. Making sure never to go to about:opera or check the settings (unless I disable the Internet first since these actions seem to trigger the auto-update feature). I also added a new variable Start > Control Panel > System > Advanced System Settings > Environment Variables > and clicked on New... in each section and added the variable: OPERA_AUTOUPDATE_DISABLED and setting the value to 1. And don't forget to change the Target in the shortcut that starts up Opera to: C:\Opera\Opera\launcher.exe –disable-update (the path should reflect the actual path to Opera on your system).
I seemed to have gained some control over my browser. Currently frozen at version 28.