There are tons of good packs available. Most of the ones you see now are internal frame. A few years back nearly all were external frame. If you're new to backpacking and do not have backpacking specific lightweight gear, I'd consider an external frame. A nice feature with external frame packs is that you can strap bulky stuff onto the outside much easier than you can with an internal frame pack.
Several years ago I bought an internal frame pack to replace a worn out external frame pack. My sleeping bag (which was a middle-of-the-road synthetic one) was so bulky it took up the entire pack. I ended up buying a new more compressible sleeping bag immediately.
External frame packs have kind of fallen out of favor, but I for one am a fan.