I would suggest minimizing the size and length of the incision. Most lipomas can be removed with small incisions.
It's hard to assess without at least a photo (and an in-person consultation is necessary for a full and complete evaluation). In general, a very small and barely noticeable incision can be made directly over the mass, through which it can be removed relatively simply. Working from farther away, while tempting because of the "hidden" scar, can actually be counter-productive since the lipoma is usually deep to the frontalis muscle. Trying to "get" there from too far away can damage the muscle and cause scarring that, at least in theory, could be more noticeable than a well-planned and healed incision right over the lipoma. Which is what I would normally recommend. I hope that this helps and good luck, Dr. Alan Engler, Member of #RealSelf500
Thank you for sharing your question. It is difficult to offer definite recommendations without a full series of photographs but the options your surgeon gave you are reasonable approaches. Because the forehead is a cosmetically sensitive area, and an incision in the hairline can achieve complete removal of the mass as well as one placed over the mass, I would be in favor of the scalp incision. Hope this helps.