I bought new because I got thousands off list (family friend doing us a favor, BIG favor), truly 0% financing (I have good credit), and the culture in my family is to drive a car until it's 10+ years old, or doesn't go anymore. I also drive cross country for work, so I need to know I have reliability for at least the next 2-3 years.
At the price I got my brand new Corolla, I'd be paying about the same for a couple year old one, so why not?
Other than that, I don't see why anyone would buy new.
What I was considering while buying a car:
-KBB Value of the car I'm looking at, as well as estimating depreciation of the car for how long you plan on keeping it, the mileage, the cost to insure, etc.
-Financing at various banks in town
-Reviews on the car. Does anything tend to break down after a few years, if so how much will it cost to replace?
-I have several mechanic family members that I live far away from now. Could I afford to fix my car without their help?
There are a lot of factors to consider. The best advice I can give is take your time, test drive, take your time, and take your time. Don't be afraid to walk away from "deals". If they want to sell you a car, they'll make you an offer you can't resist.
So, in short, new vs. (lightly) used depends. For some people, lightly used means 5K miles. Some it means 50K. I'm a fan of the cars that don't lose as much in terms of reliability/depreciation (Toyota, Honda, Lexus, etc) and have a history of good customer service. I went as far as to look at reviews of garages in my area to see the customer experience of buying a honda vs. toyota, both similar price points for me.
Cash vs. Financing:
Buying ANYTHING Cash is better. However, like I said, I put down a hunk of cash and chose 0% financing since I can use the money not going towards my car to investments like a 401K, IRA, or even my savings account at that point. Look around at different finance rates.
Only buy cash if you can afford to part with said cash
.