Depends upon the use:
I have read somewhere or other that Sierra admitted that a boat tailed bullet was harder to make concentric than a BT ..... all things being equall, including cost, then flat based bullets would tend to be more accurate....
Benchrest guys that don't care how fast the bullet is going when it pokes a hole in the paper, just so it goes into the same hole every time will say that boat tailed bullets are garbage, because they are generally less accurate.....
Hunters and long range shooters want flat trajectories and thus want the bullet to be efficient. Loss of a tiny bit of accuracy is acceptable, as an acceptable group is not measured in hundredths of an inch, but in inches. The wind will have far more effect on the bullet than the fact that the bullet is not as perfect as a flat based bullet could be......
Hunters want maximum energy on target, as well as flat trajectories.... A boatailed bullet will retain energy better at distance because it loses velocity slower than a less efficient flat based bullet. This loss of energy is relatively unimportant at under 300 ..... but when the range gets beyond 400, and the velocity begins to wane..... 100 or 200 f/sec begins to be important.
TheGolden Rule of Tool Use: "If you don't know what you are doing, DON'T."