I’m using mostly sword and dual swords and they’re both awesome. I have tried other weapons and liked almost all of them, but I just love swords, so I’m trying to stick to them. I might try kusarigamas and what not in future playthroughs. ;)
As for stances, you can stay most of the time in one of them (usually middle stance), but you’ll be more efficient if you realize which stances are better in which occasions and feel comfortable switching between them as needed. I now switch between middle and low stances very often. I rarely use high stances, but I can remember a certain boss fight that pretty much required me too, and I love it all the more for that. ;)
Of course, keep in mind that I went for a low armor, high mobility build, in which speed is life, since you’re trying to never get hit. If I had an armored/power build, I’m sure I’d use high stances a whole lot more.