regex vs htmlagilitypack

using HtmlAgilityPack;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Threading;

namespace bot_benchmark
{
    class Program
    {
        public static List<string> UrlList = new List<string>();
        static void Main(string[] args)
        {
            Console.WriteLine("Aşağıdakilerden biri Seç");
            Console.WriteLine(" htmlagilitypack \n regex ");
            string selectedmethod = Console.ReadLine();
            Console.WriteLine("url giriniz");
            string url = Console.ReadLine();
            if (selectedmethod == "htmlagilitypack")
            {
                DateTime startdate = DateTime.Now;
                Console.WriteLine(startdate.ToString("h:mm:ss"));
                HtmlAgilityPackMethod(url);
                DateTime enddate = DateTime.Now;
                Console.WriteLine(enddate.ToString("h:mm:ss"));
                Console.WriteLine(enddate-startdate);
                Console.WriteLine(UrlList.Count.ToString());
            }
            else if (selectedmethod == "regex")
            {
                DateTime startdate = DateTime.Now;
                Console.WriteLine(startdate.ToString("h:mm:ss"));
                RegexMethod(url);
                DateTime enddate = DateTime.Now;
                Console.WriteLine(enddate.ToString("h:mm:ss"));
                Console.WriteLine(enddate-startdate);
                Console.WriteLine(UrlList.Count.ToString());
            }
            else
            {
                //Todo:
            }

            Console.ReadLine();
        }

       static void HtmlAgilityPackMethod(string url)
        {
            HtmlDocument dokuman = new HtmlDocument();
            dokuman.LoadHtml(GetDownloadString(url));
            HtmlNodeCollection basliklar = dokuman.DocumentNode.SelectNodes("//a[@href]");
            foreach (var baslik in basliklar)
            {

                string hrefValue = baslik.GetAttributeValue("href", string.Empty);
                UrlList.Add(hrefValue);

            }
        }
        static void RegexMethod(string url)
        {

            Regex r = new Regex(@"<(a).*?href=(""|')(.+?)(""|').*?>");
            MatchCollection matchlist = r.Matches(GetDownloadString(url));
            foreach (Match match in matchlist)
            {
                UrlList.Add(match.Value);
            }
        }

        private static string GetDownloadString(string link)
        {
            WebClient client = new WebClient();
            Uri url = new Uri(link);
            client.Encoding = Encoding.UTF8;
            client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
            string html = client.DownloadString(url);
            return html;
        }
    }
}