what browser should i be using on my imac

Operating an Apple Computer on an Apple Operating System the Apple default Browser will give the least problems. As for features, that this subjective. There are some browsers that bring features not offered in Safari but . . how well does is operate in macOS and does it give out problems?

It comes with Safari but you can also use popular browsers like FireFox, Chrome, Edge, ...

Try them and use the one you prefer.