The Warren Tactical sights are great. They are after market and cost a bit more then the standard Glock sights. Another good optional sight to consider are the 10-8 and Heine Glock sights.
I was shooting against other officers who were using stanadard Glock sights and other known name brand nightsights. I was a bit quicker in getting on sights and follow up, sometimes that's all the differences in a gunfight. Be safe.