Comparing multiple values using If , Else if

Throw away this code and use a loop instead.

• Put the results in an array.
• Use a variable int largest_value = 0.
• Use a variable int largest_index = -1.
• Iterate through the array and for each result, check if it is larger than "largest_value".
• If the value was larger, set largest_value = the value, and set largest_index = i;, where i is the loop iterator.

After the loop, largest_value will contain the largest value and largest_index will point out where in the array this value is found.

I would store all the results in a dictionary like so (numbers are made up):

Dictionary<string, int>  myDictionary = new Dictionary<string, int>()
{
    {"Insertion Sort", 12},
    {"Selection Sort ", 35},
    {"Bubble Sort", 42},
    {"Merge Sort", 52},
    {"Quick Sort ", 32}
};

var min = myDictionary.First(kv => kv.Value == myDictionary.Values.Min());
Console.Out.WriteLine("The fastest is " + min.Key + " with a time of " + min.Value + "ms");

Which will allow you to test as many algorithm without changing your if/else structure (since you don't use it).

The output is:

The fastest is Insertion Sort with a time of 12ms

I suggest using Dictionary and Linq:

var algorithms = new Dictionary<String, Double>() { // or Dictionary<String, int>
  {"Insertion Sort", sort1},
  {"Selection Sort", sort2},
  ...
};

var best = algorithms
  .OrderBy(pair => pair.Value)
  .First();

MessageBox.Show(String.Format("The Best Sorting Technique Algorithm is {0} with the time of {1} ms", best.Key, best.Value));

The advantage of using Linq is that you can easily create a report you like, for instance let's print out algorothms from fastest to slowest:

var data = algorithms
  .OrderBy(pair => pair.Value)
  .Select(pair => String.Format("{0} took {1} ms", pair.Key, pair.Value));

MessageBox.Show(String.Join(Environment.NewLine, data));

It's not a matter with else if, but more with the operators you're using - a sorting algorithm is the fastest if it's faster than ALL others, not just one.

So, change the conditions to use the && operators instead of ||.

Please note, that this is not the best solution (see others' comments for that), it merely is a fox to your code.

I think you mean the following:)

if ( !( sort1 < sort2 ) && !( sort1 < sort3 ) && !( sort1 < sort4 ) && !( sort1 < sort5 ) )
{
    MessageBox.Show("The Best Sorting Technique Algorithm is Insertion Sort with the time of " + elapsedMs1 + " ms");
}
else if ( !( sort2 < sort3 ) && !( sort2 < sort4 ) && !( sort2 < sort5 ) )
{
    MessageBox.Show("The Best Sorting Technique Algorithm is Selection Sort with the time of " + elapsedMs2 + " ms");
}
else if ( !( sort3 < sort4 ) && !( sort3 < sort5 ) )
{
    MessageBox.Show("The Best Sorting Technique Algorithm is Bubble Sort with the time of " + elapsedMs3 + " ms");
}
else if ( !( sort4 < sort5 ) )
{
    MessageBox.Show("The Best Sorting Technique Algorithm is Merge Sort with the time of " + elapsedMs4 + " ms");
}
else 
{
    MessageBox.Show("The Best Sorting Technique Algorithm is Quick Sort with the time of " + elapsedMs5 + " ms");
}

I suppose that values of sort1, sort2 and etc can be equal each other. In this case the value with the lowest variable name is selected.:)

Change every || to && you want all of them to be true.

Change every > to <, because you want the smallest, not the greatest.

You also have a typo in your last if: you have sort5 > sort1 twice and you don't have sort5>sort4