Just about every poster has already mentioned it, but it all depends on the maker.
Takeda does a really impressive job with blue super, but I havn't use any other knives, so I dont know if Takeda is that much better than anyone else.
Ive seen a huge variance in the blue 1 and 2 knives that I've used. Blue 2 is supposed to be tougher than 1, but I had a knife out of it that had pieces just fall out of the edge every time I looked at it sideways. I also have a blue #2 deba that has pretty fantastic edge retention and great edge retention as well. I've had a blue #1 Zakurai the felt harder than my Takeda, but would microchip if used carelessly. My newest knife is one of the new Gesshin "badass" models in blue #1 and the HT is incredible hard, crazy sharp, but astonishing forgiving and (thankfully) tough and resilient enough to resist damage when I promptly buried the paper-thin tip in my cutting board during the first run.
Buy based on knife and maker, not steel.