All my training has been with flat end ones, and I carry a batonlite, so I am probably biased. Flat ends probably work better for pinch holds. Pointed ends are probably better for escapes where you need to jab the end into a muscle.
Having said all that, the last training I did we ended the session using a grab-bag of "found" items (pens, AA Maglights, laser pointers, etc.) Both flat and pointed ends. They all worked well enough to get the job done, so I don't think it really matters.
(I think it is pretty funny that Kubotans are listed as prohibited items for carry-on, but a AA Maglight is OK.)