Whatever you choose, make sure that you actually sit in whatever seat you’re thinking about buying, as different seats obviously fit different people in different ways. In my opinion, the safest-spec seat in the world becomes a safety liability if it’s not comfortable to the driver and detracts from your ability to focus on what you’re doing on-track.
I chose a non-Halo seat when I built my car 3 years ago, though if I were doing it again I would think harder about learning to live with a Halo seat (specifically, learning to deal with the potential egress challenges to be worked around.) Having now had the opportunity to drive in a car with a Halo, I found that it did not impact the driving experience or visibility at all, which was not what I had expected.
(For what it’s worth, I went with an aluminum seat, as it was far and away the most comfortable choice that I found, and was very easy to mount in the car exactly where I wanted it.)