I have a BANJO BROTHERS MINNEHAHA saddle bag. Had it for years and it looks great. It could easily be called expensive but it matched the style of bike I was using it on. So the price was worth it.
I think I have the small size. I haven't had an issue with things falling out ever. Well, if you hang your bike from the rafters your contents will fall out. But in riding I've not had an issue for 8 or 9 years of riding.
I own an acorn bag and it's nice. It has a couple different slots or areas in the bag. I just got it recently from a local bike co-op and haven't used it enough to have any complaints.
Both of these bags require loops underneath the saddle.
I've used other bags that are more athletic looking. I've had Specialized bags and other companies. They've worked just fine depending on what I wanted to carry. Have gotten ones big enough to hold my in ride tools, tube and co2 cartridges.
BANJO BROTHERS MINNEHAHA Bag