We consider the Philips brand are the best you can buy!
Philips low energy lamps come in different formats
This one has 4 small tubes giving a very even light distribution and a standard bayonet (B22) base.
18 watts of fluorescent light is equivalent to 90 watts of a normal incandesant light bulb.

Measurements:
Hieght 130mm including the base.
Diameter 48mm around the white base and 40mm around the tubes.