Hide the Grid hierarchy column, but this is basically a more complex way to achieve a TreeList-like look. You will need custom CSS to hide the hierarchy column, column templates to add custom expand/collapse buttons and custom C# to manage the Grid hierarchy. At this point I don't see a reason for all this manual work.
If you simply need to align the columns and prefer to use a Grid instead of a TreeList, then check this KB article that may serve you well: