first off, this
exact topic has been hashed over many times. search, you will find many opinions. i will add my .02 b/c i recently bought one.
i have the steeda. i love it. i believe its a little taller than the B&M, but its longer on the bottom than the B&M so the throws are the same. also, with the extra height, you dont have to reach down as far as the B&M. lastly, i have heard of some B&Ms breaking, but i believe that was a problem with the older shifters and has since been fixed (not sure though).
the one thing about the steeda is since it is longer on the bottom than the stock shifter, or any of the other short shifters for that matter, you have to make a spacer to raise the shift tower a little so the bottom of the shifter doesnt hit the floor. there is a different plate needed for some 99s and all 2000s as they use a new shift tower. i got mine through a GB, and someone made some nice machined aluminum spacer plates. i have heard of someone using plexiglass though

again, not positive.
i think the steeda is a great shifter. a big improvement over stock. cant speak from personal experiance with the B&M, so i guess take what i say with a grain of salt.
bottom line- i dont think you will be disappointed with either shifter. both are good units.