There are a lot of good and interesting arm recommendations made in this thread, but, as I said before, it is hard to attribute any particular qualities to the arm alone, particularly dynamics and a sense of being "musical." At best, one can say certain combinations of arm, cartridge and tables have these qualities as strengths (and someone may find those same qualities weaknesses).
You could argue that an arm that can handle the demands of a Decca London cartridge is extremely dynamic because the cartridge sounds dynamic. The same could be said of an arm that optimizes the performance of a Van den Hul Colibri.
Keep in mind that "dynamics" is determined by the particular table chosen. As a rough rule, tables with direct drive, idler drive and very high torque motors on belt drives tend to sound dynamic. While I am tempted to say that a lot of tables without a spring suspension also sound dynamic, but, there are plenty of exceptions to that rough call (e.g., a good Linn setup is quite lively sounding). Also, the kind of platter mat on any given table also affects the damping of vibration which greatly affects the sense of dynamics (the right mat is quite specific to each setup).
