The Specialized Hotrock 12 Girls Bike is the perfect first-choice for kids, with learner stabilisers. My daughter learnt to ride on this bike when she was 3 and hasn't looked back! The frame is lightweight and it has the benefit of looking like a proper 'big girls' bike which is useful if there are older siblings.
These bikes are just brilliant and we have purchased the equivalent boys bike for my younger son who also loves it! A GREAT FIRST BIKE at a good price (£129.99 new)