Open top works best for me. Mine is a 4 quart, the 25$ special from India. and more than I can handle. Some of the issues with the open tops can be dealt with. The hanging hole should be reinforced with a brass grommet. That will minimize the possibility of a tear-out. Brass and red rubber go well together, like jewelry for your best girl. Age is the biggest enemy of elastomer products, so inspect every few years.
Moliere recommended filling a big open-top from a graduated container. That works great! Put in what you know you can deal with. Much better than filling it too full and admitting defeat.
The larger bags usually come with a silicone hose. A tiny tie-wrap around the hose at the bag nipple will prevent the hose from coming off.
Hanging the bag from a bungee cord is great for a few reasons. The bungee hooks are steel and will never break. The full bag hangs lower, and climbs as it empties, keeping the flow rate more consistent.
The biggest difference I've noticed between open and closed tops is when the clamp opens. Sometimes the closed top bags, especially when full, will have a "suction lock", and the water doesn't flow. Pinch the hose a few times, push out, suck in...sometimes it's hard to start. Open tops go every time.
Like Reddevil said, a totally full closed top, with the wrinkled sides, is a visual turn-on.