The most accurate, or rather the highest CRI light I have experienced so far would be the McGizmo Haiku and Mule that I have.
2nd in line would have to be my legacy HDS clicky followed by the Surefire Minimus Vision headlamp. Actually I couldn't decide which of these two are better. They seem quite similar.
Malkoff M61HCRI in the MD2 host has quite a high CRI rating but the higher CCT makes it a bit too warm. Still like it very much but may not appeal to many.
Zebralight SC51C is nice too but has a slight yellowish green tint to it, have to say visually it does look quite close to the McGizmo but not quite there yet in terms of color reproduction.
The worst I have tried would be the Quark and Preon high CRI. They appear so yellowish I have no idea why and how they are high in CRI. Pee yellow is how I would describe the tint, but then in actual use outdoors it is not too bad at all.
I have not had the chance to try the McGizmo Sundrop with Nichia 085 emitter and I believe I never would since the emitter was discontinued, but I believe that has the highest CRI rating so far.
Currently I have no lights nor drop-ins utilizing the new Nichia 219 so I can't comment on that.