I would agree with steveayres. The 17-55mm is 2.8 would be difficult to improve on but do consider the 55-250mm as a second lens... yes it's cheap in both looks and price but you have a SLR and one main advantage is the ability to change lenses.
You will probably use the 17-55mm 90% of the time but equally you may miss some excellent shots due to being to far away.