gistfile1.cs

@{
    //Obviously get header from umbraco value
    
    var header = string.empty;
    var mainHeader = Model.Content.GetPropertyValue<string>("mainHeader");
    var secondaryHeader = Model.Content.GetPropertyValue<string>("secondaryHeader");
    var nodeName = Model.Content.Name;
    
    //Check if we have mainHeader value, fallback to secondaryHeader
    header = !string.IsNullOrEmpty(mainHeader) : mainHeader ? secondaryHeader;
    
    //Check again as the variable secondary header still could be null or empty string
    //This time check header variable itself. If it's still emtpy or null fallback to nodename
    header = !string.IsNullOrEmpty(header) : header ? nodeName;
}

<h1>@header</h1>

okay, i see stacked ternaries then... right!