I'm going to a purchase fixed-lens camera with large zoom.
It's hard to make a final decision like this, because cameras in the superzoom point & shoot class have converged so much that the differences aren't very important. The huge zoom range and small sensor means that you're never going to get stellar image quality, but all the camera makers have figured out how to get decent results that many people are happy with.
As you have seen, both cameras get good reviews for what they are. That's good news, because it means you can stop stressing out and pick the one you're leaning towards. If you're not leaning towards one or the other, look in the conclusion section of a couple of reviews (for example, at the end of the page here and here) and list the pros and cons that are most important to you for each camera. Then pick the one that fits you best.
The other good news is that the commitment level here is fairly low. You're not going to spend thousands of dollars on lenses and accessories, because with an attached-lens camera that's not even an option. So, if you decide you made the wrong choice, you can get a different camera next time without needing to worry about switching a whole system.
If you're not sure of the specifics right now, that's okay. Once you have taken thousands of pictures, you'll have a much better idea of the particular things you want — or want to avoid — for your next camera. The important thing is to actually start shooting, and if these cameras seem to be what you want, either one will do — as soon as it gets out of the warehouse and into your hands.
While they are both the same fundamental type of camera, there are several important differences between them. If you look at the Canon SX30 compared to the Nikon P500, you will see: