From somebody who has put a few miles on Avon Vyper Strykes, there's a lot of better tyres out there for the money and they'd be right at the bottom of my list to fit.
Keeping in mind I don't know if any of these are available in your size;
~ I've used Michelin Street Pilots a lot and have been happy with the performance
~ Any tyres I've had from Metzeler have been perfectly acceptable
~ When I was a courier I was using Heidenau K66s for winter work (all-weather, but very fast wearing) and Michelin Street Pilots for summer work.
~ Early on in my bike riding life I used Duros a lot - hard wearing and nice chunky tread (HF903?) for scooters. I can't really remember much about them, but I'm going to go back to them fairly soon I think to try again.
~ Anything by IRC - wouldn't touch again with a barge pole
~ Anything by Maxxis? See Michelin Street Pilot, I liked these a lot too
~ Conti-go (Twists?) seemed nice and sticky but I didn't have them very long, which I regret now.
Anyway, hope this is of use to somebody and not just a rant... I've tried to keep it scooter-specific.