Canon  Speedlite 430EX is very good in performence, it is choice of millions of people.  

Canon Speedlite 430EX Specification, Features: –

Type Mode: E-TTL II, E-TTL, TTL
Zoom positions : 24mm, 28mm, 35mm, 50mm, 70mm, 80mm, 105mm; 
Flash Range : ISO 100, with EF 50mm f/1.4
For normal flash : Approx. 2.3-79.7 ft./0.7-24.3m
For high sync speed : (EF flash) Approx. 2.3-39.4 ft./0.7-12m 
AF Assist Beam : Built-in; covers all focus points in EOS cameras up to 9 AF points
At center : Approx. 2.3-32.8 ft./0.7-10m
Periphery : Approx. 2.3-16.4 ft./0.7-5m (in total darkness)
Custom Functions : Six user-selectable Custom Functions built-in; set on Speedlite’s LCD panel
Power Source : Four AA-size Alkaline Batteries (6V); Four AA-size Ni-MH (4.8V)
Dimensions : 2.8 x 4.8 x 4.0 in./72 x 122 x 101mm
Weight : 11.6 oz./330g (without batteries