I like the Fate system for its simplicity and flexibility. The spellcasting system especially is very versatile, although it is also the most complex part of the game. However, once you get a handle on it, in practice it becomes very simple. I haven't actually played a game with the system, but I've been looking it over for the last couple of days and it seems like a very straight-forward, story-driven system. Also, you need to decide whether you want to use the official rules for the DFRPG, which is based on FATE 2.0, or the new FATE 3.0 rules. Several things have been tweaked, but consensus seems to be that FATE 3 is all-around the better system. A lot of the rules and options have been streamlined for ease of play. However, that does mean you'll have to do some converting. For example, the way Extras work in FATE 3 is slightly different than the way Powers work in DFRPG. For example, in the F3 book they basically lump all magic under one Extra that's dependent on the Lore skill, whereas in DFRPG spellcasting is a Power dependent on two skills, Conviction and Discipline, and each spell has its own individual prerequisites and parameters. Like DFRPG though, powers like super strength or resilience cost points of refresh to buy; meaning you start each session with fewer fate points to spend in exchange for having this nifty power you can use at any time. I'm fine doing it either way. My suggestion is that not everyone play a spell-slinging mage. It would be better to have at least one vanilla mortal, and at least one super-powered mortal like a werewolf or Red Court infected. Dresden Files is in general a pretty low-magic setting, and a party of five wizards would probably get boring quickly.