In my opinion there is no one answer to this question (frustrating I know!). There are several factors to consider - your learning style, your potential career plans etc.
If you learn best in smaller groups, and with more one-to-one attention, then picking a smaller school is likely to be a good fit for you. For subjects in the humanities liberal arts schools often have the best programs. I personally chose a private, liberal arts school for several reasons - first, I was interested in attending a faith-based school (I'm hoping to enter a career in ministry, so this one was a bit essential for me), but most importantly for me, was that I learn better in smaller class settings, and through discussion based learning than I do through lectures.
By contrast, if you're interested in science, a large research university with good lab facilities, and the opportunity to do research with professors might suit your needs more. For people majoring in business, the strenght of the school's connections with local, regional, and national businesses can make a big difference in terms of internship opportunities and down the road job opportunities. If your biggest goal is to simply graduate and make as much cash as possible, then school's with wealthy alumni associations involved in high-profile companies may be a plus for you.
Sorry this isn't a simple answer, but I've learned that when it comes to what college is best, the answer is different for every student!