Flux for me too, been with them about 5 years for my self build camper and other times with classic cars etc. Never had a problem with them and always been treated well when I had to speak to them over the phone.
Last renewal I haggled and got about £100 off my premium. I paid £245 and think thats hard to beat.
My only grumble with them is their breakdown service, Flux Rescue. At £85 per year its a bargain, but you need to take it out within 2 weeks of your insurance starting. I have been with AA for about 5 years and unfortunately it renews about 4 months later than my insurance, so I`d either be doubling up for 4 months or doing without breakdown cover for 8 months. Still, when AA was due for renewal, I haggled again and got it down to £90 from £135.