Here's an article on sway bars by Tim Skelton. Very informative, as are all his Lightning articles. It appears, that despite being heavier, the Hellwig is the stiffest bar by far, front and rear.
Tim Skelton's take on anti sway bars
Some numbers from the article. Percent stiffer than the factory bars. Look at that rear! 144% stiffer than the factory Lightning bar!
Front Hotchkis 82%
Rear Hotchkis 26%
The Hotchkis bars weigh 16 pounds front and 6 pounds rear.
The Hellwig bars weigh 29 pounds front and 17 pounds rear.
I've got a Hellwig on the rear of my Ranger, which came with none stock. It's a good handling Ranger. Should replace the front with one as well.