When I was picking a college to go to, my choices were pretty limited. My parents wanted me to stay within a fairly short distance from home, and there's only a couple of colleges in the area that offered what I wanted to major in. So I pretty much just stuck with whatever one seemed to have a better reputation.
Class size can be pretty important. It depends on how you learn. Some people work well in larger classes. They're more self-motivated and have the ability to learn some stuff on their own when they don't understand something. Other people do better if they can get more attention from the teacher, and have a smaller working environment. Sometimes you just don't have a choice either way, but it is a good thing to think about. Class sizes can vary of course even within one school though, but if you ask different places how many total students they have, then compare them, the schools with more students will naturally have larger class sizes, on average.
It's necessary to think about the location of the school too. It can determine whether you commute from home, or live at the school or in an apartment on your own. Personally, I highly recommend NOT living at home, at least for the first year, simply because it is a good life experience. Also, depending on how much you get along with your family, being closer to home means your family sticking their nose into your business more often. And on the other hand, being farther from home means seeing family (and maybe friends too) less often, which some people have a harder time with than others.
One other thing is that you should not determine where you go to college just based on where your friends are going. Not saying that it isn't nice to have someone you know, but sometimes being forced to make new friends in a new place can be a good thing. And sometimes, even when you're at the same school, old friends can go off and do their own thing anyway. Pick a school based on what's best for your education, not your social life.
These are the things I considered when I went through the process. Things may be different for you, of course, but thinking about stuff like that should help you pick a college that's best for you.