I've used GPRs, 090s and Metzeller M1s and as an all rounder it has to be the 090 for me awesome grip in the dry and knee down at Cadwell in the wet. The GPRs IMO were as good as the 090s in the dry but didnt come close in the wet as for the metzellers again nice and grippy in the dry but never tryed them in the wet.

so I would say most of the tyres I have mentioned (for road use anyway) are much of a muchness as you will never push their dry limit on the road anyway and if like myself you try hard not to get caught out in the rain then it just comes down to price.
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MC21SP - Roth-tax
CBR400 - track
MC21R - sold
MC21SP - sold