The Kawasaki bags are a poor bargain on a $/lb basis - they are small and expensive.
A better option in the smaller size is the Cortech Sport Bags
. I have had these and found them acceptably well constructed, but the zippers are crap.
A larger bag is the Nelson Rigg CL 850
. I use these bags extensively and feel they are top notch bags.
Nelson Rigg also make a smaller sport bag similar to the Cortech. I have not used them so can't comment, but I would expect them to be very good.
For multi-day camping I use the Chase Harper Alaska bag
. It will hold my entire camp, food, and civvies. Once camp is set up it can collapse down fully with its compression straps to hold as little as a spare tube and tool kit, a canteen and munchies for day rides.
I think all of the above are well made and well priced.
For hard cases, most use either the Pelican or the SeaHorse cases. They are pretty much identical, but the SeaHorse are less expensive. Some use ammo cans or Mermite cans. Some use purpose-built aluminum panniers from Happy Trail or Twisted Throttle. These tend to be the high end of the cost spectrum.
Hard cases will require a $$$uitable rack and will bang the hell out of your calf under the right circumstances. Soft bags usually require only a rack-$orta-thing to keep the bags off of the side panels.