I'm thinking of buying a scooter (never had one before) and wondered what make of bike is the better one to buy and which models should I steer clear of?

All answers welcome

For price, speed and fuel economy I would look at 125-150 cc scooters. With that size you will be able to keep up with traffic on average roads (45-50 MPH limits). If you go small (50cc) it isn't powerful enough for that type of riding.
Popular and well made scooters in that range are the Genuine Buddy and the Yamaha Vino 125. They would be good starter scooters and hold up well.
Vespa makes a 150 but you will pay a lot more for the name.