Find The Most Occurred Word In String

public string ReturnRepeatElement(string str)
{
    int i, j;
    int maxcount = 0;
    string[] strArray = new string[]{};
    string _element=string.Empty;
    strArray = str .Split(' ');
    for ( i = 0; i < strArray.Length; i++)
    {
        int count = 0;
        for ( j = 0; j < strArray.Length;j++ )
        {
            if (strArray[i] == strArray[j])
            {
                count++;

            }

        }
        if (maxcount < count)
        {
           maxcount = count;
           _element=strArray[i];
        }
    }

    return _element;
}