Both are good ecus and can have different modifications. The standard moded ecu has higher rev limit, no boost/ fuel cut, and slightly more agressive timing maps. Some are configured for larger injectors. The thing is that they are bought used most of the time and unless you get one from a JDM clip or engine set, you dont really know what has been done to them.
I had a Mines ECU that came with my 1jz clip, it was awsome!! It made up to 550 RWHP with an SAFC. The Blitz ECU's seem to crap out more than the Mines ECU's, I have personally seen 3-4 blown Blitz ECU's and no blown Mines ECU's....take that for what its worth.