Honestly, foam is probably the easiest material to work with and it has some pretty decent results with a bit of patience and practice. My ODST helmet was... okay[?] as a an early attempt and I've since had a load of practice.
The trick to foamwork is honestly edge preparation. Not all surfaces are meant to be flush mating surfaces and adding edge bevels to reduce transition angle will help reduce the pirate hat appearance. Sanding down sharp corners and rough edges that shouldn't be there is also an option. It's hard to make suggestions without seeing any pictures of what you're unhappy with but if you uploaded some, it'd be awesome.
My current kick right now though is 3D printing buckets. Current progress on my CQB helmet after about 3 hours of fiddling around in Fusion 360 and a finished project that has been printed and sent off to another forum member.
3D printing a helmet is "easier" in the regard that you're getting exactly what your pattern is within a small margin of error, the downsides are the high startup cost, the skill requirements of making your own models, the endless hours of surface preparation and depending on how you finish them, the lower durability of the finished piece.