If you have self-control and have the ability to put school before partying, then go for UCSB. If I were in your position, I'd go for UCSB. It seems like you really care about the environment you'll be living in and honestly, UCSB is located in an amazing part of California. They're both amazing schools. But then again, UCI's biology program is better than UCSB's. It just comes down to if you're willing to sacrifice a bit of prestige, I guess you can say, for a better/more comfortable living environment.