I've used Hagerty for many years. Full coverage (C&C and liability) runs me around $200 per year for a vehicle with an agreed value of $35,000.
I had a total loss claim with Hagerty and it was settled four days after the incident without question or hassle. I figure if Jay Leno insures a collection valued at over $100,000,000 with Hagerty (his premium is estimated to be around $1,000,000 per year), they're good enough for me.
Whatever company you decide to go with, be sure you get a policy with an AGREED VALUE for the vehicle rather than a Stated Value. The difference is that with an Agreed Value policy, both parties agree in writing as to the total value of the vehicle. In the event of a total loss, you will be paid the entire Agreed Value.
A Stated Value policy means that you tell the insurance company what your car is worth and they take your word for it and charge you a premium based on that number.
In the event of a total loss, the insurance company will pay you what THEY believe is the fair market value of the vehicle rather than the figure you told them. Maybe the numbers will agree, maybe they won't. They usually don't, especially with customized vehicles whose market value is entirely subjective.