Well Metallica is now and has always been classified as metal. And one of the most influential metal bands ever.
The Black album had some good songs on it. Though not a fan of Enter Sandman. Could be because I grew up more familiar with their older music. Their thrash days. When they hopped genres to do something more mainstream accessible they got a lot of backlash from their old fans. I felt a negative when Enter Sandman came out, for the same reasons others did.
Eventually I got over it and enjoy the Black album now. Though perhaps my initial dislike of the change stuck with me.
Sad But True and Nothing Else Matters were my favorites. But anything after that album I lost all interest. I tried their Death Magnetic album, it's not bad but it didn't really grab me.
You may dig Skillet. Not really my thing but they're quite popular. Lacey Sturm. And also Flyleaf, Lacey Sturms old band. Their earlier stuff was best, to me. When she quit I lost interest.
Project 86 would be considered alt metal, though perhaps too heavy for you.
Off the top of my head that's all I can think of to recommend.
