I would argue that #2 is better with tau; yes there's a factor of 1/2, but it should be there for the same reason that kinetic energy is 1/2mv*2 and distance tr

I would argue that #2 is better with tau; yes there's a factor of 1/2, but it should be there for the same reason that kinetic energy is 1/2mv*2 and distance traveled under constant acceleration is 1/2at*2. All of those are the result of integrating a linear function.