ZX6Rs (G, J or A) are a great first bike IMO.. not a full on race rep but more than capable in the right hands.

The 636 engine is great too.. surprising more midrange than the equivalent aged 600 of other makes..

Just get used to stripping and cleaning the 6 pot calipers after every winter.. They are great brakes when in top condition but they go off quick once the grim sets in and with 12 of everything (seals, pistons etc) they cost a fortune in bits alone...

enjoy...