I'd recommend Unknown Armies, most likely a street level campaign. Its an incredibly simple, yet elegant system based off percentile dice, but without the charts normally associated with d100 based systems, and the outcome allows for a better range of successes and failures without resulting to the storyteller system's "fist full of dice" that basically assures success.
The world of it is what really intrigued me, with its emphasis on obsession and passions. This bleeds over into the magic system schools. Cliomancy for instance, is obsessed with the relation between place/people and memory. Its adepts draw their power from charging from historic locales, and channel that into altering memory and perception. In the case of most schools, just charging up fuels good role playing in itself. Its got a list of formula spells, but each school has its own random magic specialty that allows players to invent effects on the spot.
As far as the beastiary goes, its somewhat light compared to a monster manual. There are some creatures and constructs to be found, but the system is simple enough for you to wing it, and the combat guidelines are good enough for eyeballing damage. However most conflict can occur within the occult underground, the cabals and weirdo's who are in the know, and vie for power.
It lends itself to giving a grain of truth to urban legends and our own weird history, particularly if you're players are willing to get involved and do some research. I had an entropomancer go dig up the grave of Anthony di Stasio, a child who surfed (and survived) a 35 mile per hour 40' tall wave of boiling molasses in the Boston Molasses flood of 1919 to get a bone to make an enchanted skateboard. Its definately a very different feel than CoC.
