I used Blue Steels from the time they were introduced until I stopped playing in the mid 90's. When I picked the bass up again earlier this year, using Blue Steels gave me a point of reference from previous experience; kind of reacquainting with an old friend. My Charvel 4B with EMG's are using original Blue Steels, and I've got Blue Steel Nickles on my Sterling SUB SB4. The Nickel is a little less crisp and kind of a mellower tone. I like the original Blue Steel a little more; they've got a clarity and a fuller tone from the stainless steel that the nickle plate doesn't. However, if you're looking for a mellower tone, those are a fine choice.
I recently tried a set of the Dunlop Heavy Cores on my Thunderbird because many of the songs my current band plays are in drop C and medium gauge strings were too rubbery in that tuning. These are the first Dunlop strings I've tried, and so far I've been very impressed with their life and the strong fundamentals they provide. Blue Steels do harmonics better, but those Heavy Cores were just what the doctor ordered for this particular gig.
Of course I get all my strings from bassstringsonline. com