Well, once you take all those lovely programming features (They can sure spoil an artist, can't they? 
) out of the equation, there isn't a whole lot of difference between the two. Both types will successfully heat your silver and/or glass up to fusing temperature.
But that being said, there are a few pros and cons to each:
-Exposed coils need a tiny bit of extra caution. You don't necessarily want to go poking around at them with a metal kiln fork.
-Overall brick is a bit sturdier; fiber can break down more easily in the long run.
-Fiber is lighter weight – an aspect you should take into consideration if you'll be moving your kiln around much or travelling.
-Perhaps the biggest difference is that fiber will heat up more quickly than brick. So if you're an impatient kiln user, that may be your deciding factor.
Good luck and happy kiln shopping!