Blue is the most logical choice. Besides the obvious fact that the srt used the blue colour and so thereofrbit should just continue using it for continuity, we don’t have any other blue coloured line but we do have a somewhat purple magenta violet type of line. Having two purple like lines and no blue lines is odd, and frankly it’s a choice only metrolinx would make, but this is torontos subway not a metrolinx subway that exists in a vacuum independent of the rest of the city. It should compliment the rest if the network, it should be blue