Does lowering taxes really stimulate city growth?
So far in my games I haven't found any noticeable difference with lowering taxes below the default. The main driver of residential growth seems to be the availability of jobs, with high unemployment leading to reduced residential demand and underemployment leading to higher demand. There's also a limit to the number of people that can migrate in at a time, so if there was once some benefit, we can't see it because of this migration limit.
Note that tax rates above 12% will cause citizens to complain and eventually move out, but any difference between 12% and 1% seems to be negligible enough to not matter and is outweighed by other factors.
Thus, it seems harmless to just set all taxes to 12% as soon as you unlock the tax milestone.