Just visit both types of schools and see which one you think you would like better. I personally enjoy small schools more...easier access to professors (they notice when you're absent, help you stay on track -which is VERY important during your freshman year, heh- and all that other good stuff), resources such as lab materials, and less competition when signing up for the classes and times that you want. Having a bad schedule can just completely ruin your semester.
Large schools will generally have more social groups and clubs, anonymity, etc. They usually also tend to have more of the expensive equipment such as electron microscopes, telescopes, and so on (unless of course you go to a prestigious and small private institution).
But as I said above, the best thing to do -if you have the opportunity- would be to visit the campuses of a small and large school, ask around about what students like and dislike, and then see which would suit you more. Good luck with your choice.