For general dismantling work during renovations, most pry bars will do; removing millwork intact for re-use without damaging adjacent surfaces calls for a more specialized tool like this one. While expensive, since it's really just a bent piece of steel, it works very well.
Used with a hammer or mallet, it has a thin, bevelled edge to slip between the wall and trim and a steep, integrated 15° wedge that acts as a pry, gradually forcing the trim from the wall. The 4" wide blade spreads contact over a broad area, reducing the risk of marring surfaces.
Made of high-carbon steel with a vibration-absorbing handle.