Which glock is best for me?

I am currently in college and am looking to purchase my first glock. Im getting my concealed carry permit in a couple months and am looking at the G19, G23, and G36. I will mostly carry it in my vehicle but will occasionally carry it on me. I was leaning towards the G23 .40 cal since its in the middle but a cop told me they aren't as good as the 9 mm or .45 cal and don't have as good stopping power but I don't want to have a weak round with the 9 mm or a super expensive round with the .45. Please give your input for someone who will just shoot every once in a while and mainly carry in the truck but still wants plenty of power to back me up. Thanks