What Browser to use with OS 10.12.6 when I don't want to upgrade and Safari is not doing the job.

I have a Mac mini and I want to run Sierra on it because I use an older version of Photoshop, CS3 and it won't run well on anything newer. I can't upgrade Sierra 12.1.2 unless I upgrade the OS and recently there are just too many things that this version of Safari won't open. Is there a browser that I could use that would work with this old OS?