I’ve used REIS, Manning and Classicline for road and track cover on my cars. All good, pros and cons to each, and different approaches to how they structure the cover.
REIS have become less flexible and more expensive over the last few years. I’m not using them at the moment but they were excellent when I had a major accident in my Elise and it was a borderline write off. They let me use my own Lotus specialist to assess and estimate the work then reviewed and agreed to fund it.
Manning have very flexible cover and you can structure a mix of miles between personal, commute, business and track if you need a mix. They’ll do agreed value cover and include 6 track days per year for a modest extra (IIRC £70-100). They aren’t always the cheapest of the specialists but usually quite close, within £50-100.
Classicline were more price competitive this year (I moved 2 of my 3 to them in March and May). They include 6 track days as standard, so are more expensive if you don’t need that as you can’t remove it. Good agreed value cover. Usually the same underwriter as Manning.
All 3 are Lotus specialists and are geared towards second/weekend cars. That suits my usage, so I don’t know how they are for daily drivers. When I wanted to add more annual mileage on the GT430 with CL they did say going over 6k miles per year would put the premiums up quite a lot.