Bluffside all the way
While MEG produces very good books focusing on many different areas, Thunderhead's Bluffside was/is the best. The completeness of the city combined with the massive number of ways to use it in a campaign make it one of the best books ever produced for d20. I think all Bluffside fans would welcome another city effort by the same folks that produced Bluffside.
Artificer's is also a very well thought out and well presented book. Although seemingly a little complex at first, once you delve into the system, it becomes almost second nature. Another fine product from MEG.
Rabid Gerbil
"Watch out or I'll bite ya"