I go for both accuracy and velocity, why choose? I work up different powders one grain at a time with cheap bullets till I see a spike in velocities on the chrono or other pressure signs, then I back it down a grain or so (staying within published load data of course). Then I load the ones with the highest velocities with a few different types of bullets that I prefer and choose the one with the best group. I then test it in summer temps in the 70's to make sure there are no excessive pressures (the higher the temp, the higher the load pressures). I prefer the Hogdgon Extreme powders because they are less sensitive to temperature differences. I have found no difference in velocities tested at 25 and 70 degrees with the Extreme powders. Some powders I have tested shoot 150 fps different at those extremes which effect your groups. I don't sacrifice accuracy or velocity the way I work up loads. I go for both. I'll probably catch hell from somebody for the way I do it but it has safely worked for me for the last 20 years.
