So far, and I've only read the first three books, I've found merits in each that the others don't really possess.
TBC is the best in terms of how deeply you're immersed in The Black Company, but I thought that Shadows Linger posed more interesting views of good and evil. I also liked the setting of Juniper, and the break from first person narrative for characters like Shed. He was a favourite.
I'm almost finished The White Rose and I've really enjoyed the three separate plotlines (although it's down to one now). I'm going to have to wait another fortnight before I can get the next installments though! *Cries*
Is it worth buying The Silver Spike? No one seems to like it.
LR