You don't have to look any further than Noah's Ark to realize that the bible is more violent than the Quran. God killed every single person and animal in the entire world that was not on the Ark. Think of all the innocent people who just didn't want to get seasick. They were all murdered.
The Bible and the Quran are both violent, but the Bible is more violent, due to it being both a larger book and containing far more violent and grisly stories than the Quran, which is largely just a book of commandments. Both do contain horror stories anathema to modern sensibilities, but the Bible is even more so.