I also have thick hair and an oval shape. Had to get a new helmet when I got my hair cut. Most better helmets are not designed for and/or “legal” if hair is put up in them. I am happiest in my Charles Owen Pro II and also have the CO Jr8?.. not sure of the model number, both are skullcaps as I event and prefer a brimless front. The best helmet is the one that fits properly and suits your discipline needs. CO also makes a pretty nice one that looks more like a hunt cap (Wellington) that offers a lesser profile than some of the mushroomy types. I have coveted this one for many years and will likely break down and make the purchase some time this year. The Wellington looks nice, even appropriate, in the dressage ring.
I suggest a trip to a few tack shops, look around, try on as many different models as possible. I don’t think there really is a BEST brand out there, the one that fits correctly is the best one ; ) Figure your size in a few models, then shop on line for a better price if there is one. Remember to make sure that the one of choice is properly certified (ASTMI and some have safety codes as well, usually a number: 1, 2, or 3).
Sure there's right and wrong but mostly there's just a whole lotta different.