Personally love R888s. Grip well from cold. Soft ish though IMHO
Currently using Yoko A048s - similar grip to R888s, but take a lap longer to grip properly. Slightly longer lasting than R888s
Have used Yoko A046s as well for one event, not as good as 48s.
Yoko C Drives - hard wearing and grip well, but not as well as R888 style tyres.
Have used Slicks - Yoko Advans. Cheap, grip like R888s but last longer oddly! Was expecting huge grip, but think they are more endurance focussed... If you have spare wheels and tracks that allow them slicks are the way forward.
Not used Dunlops (D02J etc) but know Mike R uses them with great results, and he knows his onions so worth looking into. Roughly 50% more pricey than R888s for the same size tyre.
R888s for me, bought from Martin is my personal choice

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Si