Well, I'm sure you'll get a lot of recommendations for Alien Bees, and I'd second that. And the Vagabond battery system is cool, too. You won't get anything better for the price.
I've never used them, but my next lighting system will likely be from Hensel. Alien Bees are monolights, and I really like using them on location, but I personally do prefer a pack system for studio work (right now I have one small Dyna-Lite pack, which I've never had any problems out of either, btw). Hensel seems to have all the bells and whistles I'd want without the Broncolor price tag.
Several photogs here use Hensels and love them.
As for things like light modifiers, I only own one softbox, and it's a Westcott. I think it's great, and I'd buy their stuff again. I'm also looking at Photoflex's stuff, too. Their stuff seems less expensive overall, but from what I've heard here it's quality stuff.
Well, at least half of what I've said is about things I haven't actually used, but maybe it's at least a start?