I've always got along with Porto but starting to look at alternatives since i'm getting a lot of issues with google pagespeed CLS score. I'm thinking a long the lines of Claue or Fastest.
It simply doesn't exist. All themes/extensions have bugs and sooner or later it will be reported on Github (open source extensions) or Themeforest (paid themes). You can take a look at "comments" link on every single theme on Themeforest, there is always someone reporting a bug/question even when Magento has not been updated for months. Sometimes it is related to version of Magento, sometimes it is related to PHP version. There is no point looking for a theme without bugs.