before you decide to pick a car, do educate yourself as others have stated...edmunds.com is a good site IMO. they did a series of atricles about a year ago where they sent a reporter to be a car dealer for a few months. It was pretty enlightening the tricks they do.
also, believe what you read about the cars yourself, 75% of what most salemen say is crap in my experience. They either make it up because they don't know or becasue they want to make a sale - when looking to buy a used civic with no AC in AZ, "you can buy it and then put in an AC system for about $200". What?! A compressor alone would have costed me more then that. This guy either pulled a number out of his butt or figured I really didn't know what was going on
next, before you pick your cars, decide what you're going to be doing with them. If you're into mods then a scion or civic are pretty easy to work with. if you use this for utility and want to go on long road trips with friends, maybe a 4 door is more your style. if parking is an issue on campus, a smaller car may be better. point is, think about what you're using the car for before you buy it
similarly, think about how long you plan to have the car. most car's lose about 10-15% or more of their value in the first year so if you're only going to keep the car until you're out of school why should you eat that price. if you're going to keep the car until it dies, then maybe new isn't such a bad idea. all the cars you've listed have good reliability, so I wouldn't be concerned about that.
service - are the dealer you're planning on buying from close to your shcool or is there another dealer nearby. since the car may be under warrenty you want to make sure you can take it somewhere you don't need to pay to fix things.
i'd recomend going to some places like a saturn and ford dealer or places just to practice negotiating first. if you get marked for a "car virgin", they'll likely try to take you for a ride and not in a good way. test the waters with dealers you don't care about so you learn their tricks, style, and process, then go to your dealer of choice. if you can, have someone you trust go with you for an objective opinion
finally, if you ever feel like you're getting a level of pressure you don't want or a salesman that makes you feel uneasy. just walk away. you're not looking for some exotic beauty - there are plenty of cars and plenty of dealers