I was wondering if airbags are better to own or springs for lowering my car?

It might be more expensive, but my personal opinion is that airbags will give you a better ride on most surfaces.

then dont lower your car... that's the easy answer. otherwise look for spring options. i highly doubt there is any aftermarket support for air bags on a sentra...

Drop it on some coil overs

you can go either way. just depends what kind of budget you are on or what direction you are going with your car. Airbags will give you a better ride but are more expensive. But will have a better ride If you live on a dirt road i would go with coilovers or springs. Also cheaper. Don't forget to get your car aligned after lowering your car!

If you live on a dirt road make sure that if you buy the coilovers get the tien's so that you can adjust the dampining from inside the vehicle that way when you hit the dirt road you wont have to run around the car to adjust it to full soft. It's seems like it would be easy to do but it gets tiresome