using System;
using System.Collections.Generic;
using System.Text.RegularExpressions;
 
 
public class Test
{
	public static void Main()
	{
        string pattern = @"<Etiqueta>([a-záéíñóúü]+)";
        string input = @"Hay datos <Etiqueta>que [re]quiero <Etiqueta>Hola que tal";
        RegexOptions options = RegexOptions.IgnoreCase;
        List<string> list = new List<string>();
 
        foreach (Match m in Regex.Matches(input, pattern, options))
        {
            list.Add(m.Groups[1].Value);
        }
 
        string[] Datos = list.ToArray();
        Console.WriteLine(string.Join("\n", Datos));
	}
}

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