Being a professional double bassist, I use the Roth & Junius BSB-02 4/4 Soft Bag soft bag most days, to bring my bass to symphony hall, and to various gigs.
It fits my big, violin-cornered, old French bass just right, and, due to its generous padding, I feel that my instrument is quite safe in any situation. It has just the right amount of handles in the right places, as well as the backpack straps, which can be used together, rucksack style, or old-school, just slung over one shoulder. Also, the stitching is great, has lots of pockets, and it really stands up to soft bags three times this price. Can't think of any cons and would recommend it to anyone.