My experience has been that the GMail interface is slow, and I'm tired of it nagging me to install the GMail app. If I wanted to install the GMail app, I'd use my phone, not my computer.
GMail's spam filtering was best-of-class years ago. That's why so many people switched to it. But now it's mediocre at best. I can only shake my head and wonder how some of the so visibly obvious spam messages get through.
In keeping with the spirit of the OP, I'm not going to recommend a better option. They're out there. And with GMail getting worse by the month, it's worth keeping your eyes on the competition to see when you might want to make the switch, too.
Google Search is also supposed to be terrible. I don't use it, but my wife does and she complains about it all the time.
Recently she was searching for information about drinking white wine with beer. It's supposed to be a thing in New Orleans. She wasn't able to find anything but ads and places selling white wine and/or beer.
Right now, searching Google for "white wine and beer" and "new orleans" I get a blog post about Christmas in Australia, "Beer Drinking African American" stock photo, Pinterest spam about beer buckets, and a bunch more blog spam. Nothing useful. I see no reason to go back to Google for anything.