RunAsync1, RunAsync2, RunAsync3 have the same output. What is the difference between them? What is the best practice (design and performance)? thanks!

       public static void RunAll()
       {
           RunAsync1();
           RunAsync2();
           RunAsync3();
       }

       public static void RunAsync1()
       {
           Console.WriteLine("Starting calc");
           var task = Task.Run(Calc);
           Console.WriteLine("Do more...");
           Task.WaitAll(task);
           Console.WriteLine("END");
       }

       public static void RunAsync2()
       {
           Console.WriteLine("Starting calc");
           var task = CalcAsync();
           Console.WriteLine("Do more...");
           Task.WaitAll(task);
           Console.WriteLine("END");
       }

       public static void RunAsync3()
       {
           Console.WriteLine("Starting calc");
           var task = Task<int>.Run(GenerateNumber)
               .ContinueWith(tsk1 => Increment(tsk1.Result))
               .ContinueWith(tsk2 => PrintNum(tsk2.Result));
           Console.WriteLine("Do more...");
           Task.WaitAll(task);
           Console.WriteLine("END");
       }

       public static async Task CalcAsync()
       {
           var num = await GenerateNumberAsync();
           var num1 = await IncrementAsync(num);
           PrintNum(num1);
       }

       private static void Calc()
       {            
           var num = GenerateNumber();
           var num1 = Increment(num);
           PrintNum(num1);
       }

       private static int GenerateNumber()
       {
           Thread.Sleep(3000);
           Console.WriteLine("Generated number = 5");
           return 5;
       }

       private static int Increment(int num)
       {
           Thread.Sleep(3000);
           Console.WriteLine("Increment number = 6");
           return num + 1;
       }

       private static void PrintNum(int num)
       {
           Console.WriteLine($"Num={num}");
       }

       private static async Task<int> GenerateNumberAsync()
       {
           await Task.Delay(3000);
           Console.WriteLine("Generated number = 5");
           return 5;
       }

       private static async Task<int> IncrementAsync(int num)
       {
           await Task.Delay(3000);
           num++;
           Console.WriteLine("Increment number = 6");
           return num;
       }

RunAsync1, RunAsync2, RunAsync3 have the same output. What is the difference between them? What is the best practice (design and performance)? thanks!