scythian2000 seems like somewhat off topic here, but the reasons are: Slower than chrome, lags in web standards, web apps are unreasonably restricted, less secure across pwn2own competitions, evaluation by many academic papers, etc., no movement towards memory safety at the level of rust (swift is not rust, and thus suffers from specific types of memory vulnerabilities), and chrome is recommended by most security firms and experts over anything else for security.
On the more subjective side, I disliked safari browsing experience when I used it, mostly because it misrendered some websites I used to visit a lot.