A large university is a more suitable place to spend years in one's 20s than a small college for several reasons. A large university is a more suitable place to spend one's 20s than a small college for several reasons.

If you choose a small college to enroll in, it's difficult to make friends who major in different fields or who have unique backgrounds. If you choose a small college to enroll in, it's difficult to make friends who major in different fields or who have unique backgrounds.

Second, large universities tend to have competent professors and offer attractiveinteresting classes. Second, large universities tend to have competent professors and offer interesting classes.

"Attractive" isn't wrong, but I think "interesting" fits a bit better.

I assume that they have to make efforts to draw students' attention because less interesting classes are supposed to be disappeardiscontinued. I assume that they have to make efforts to draw students' attention because less interesting classes are discontinued.

In addition, you can use well-equipped facilities or receive a financial support from the university when you apply for exchange programs. In addition, you can use well-equipped facilities or receive financial support from the university when you apply for exchange programs.

In this context, "support" is an uncountable noun, so we don't use "a" before it. Alternatively, you could say "receive a financial award" if you're talking about a specific scholarship instead of general financial aid.