I have the Wheeler set (72 pcs?) with removable bits and different length handles. Seems very good quality. The bits are hard and very sharp. It includes a huge range of thicknesses, widths, slotted, phillips, torx, and specialty ones for various firearm brands/models' unique fasteners.
The main thing you want are gunsmith screwdrivers that are concave profile rather then the general purpose chisel profile drivers. This gives the tip a straight wall on both sides and fills the rectangular slot of the screw head, reducing the chance of the bit slipping out.
I think Brownell's sells their own brand of removable it drivers. Everything I have bought with the Brownell brand has been top quality so I expect their screwdrivers would be good too. So far my Wheeler set has matched every need and performed well.