You didn't really mention your intended use (around town? day hiking?) so I'll just tell you what I have.

As a large-ish pack for dayhikes, or a small-ish one for overnighters, I really really like my Deuter Futura 32. This thing is built like a tank and has tons of useful features. Extremely well made. Very comfortable. More for hiking than around town use in my opinion, but I suppose could be used either way. Deutra make many other sizes if you need something smaller or larger than 32 liters.

http://www.deuterusa.com/futura32.html

Sold at REI for $99, a typical price I see in local stores as well:

http://www.rei.com/product/47840357.htm