I've had the same question...I decided to go for riser bars, but that's also because I inherited a slightly-too-big-for-me bike with drop bars, and I couldn't really reach the brakes. The stem was also really short (80mm), so I wasn't sure how much shorter I could go and how much difference it would make. I put on drop bars, and it's way better.
But there are also some good options out there for adjusting the stem. If you like to be more upright, you should check this out - gives you options on the height, and looks easy to adjust.