Camera bag recommendation

A small sling bag that is versatile and fits your needs could this: MEC Right Hand Pod Sling Bag (or left hand)

It's only C$23.  I've used it to carry a small kit for a hike outdoors.  It can easily fit 1 camera, 3 smaller mft lenses, spare battery, filters, small first aid kit, cell phone, wallet, snacks and water bottle.  It's tiny and light.  Because it's a sling, access is as easy as pulling and sliding the bag forward without having to remove the strap (like a backpack would require).

Yes it's not a real camera bag in the sense of not having padding but just inserting the removal pads from other camera bags instantly provides the protection.

On the other end of the money spectrum, the ONA Brixton is a wonderful bag.