IZIP has been manufacturing high-end, affordable electric bikes since 2005. We think the IZIP E3 Dash is the best of the bunch. This class 3 pedelec delivers power as you pedal taking you to speeds of 28 mph. It's fantastic for your commute, especially if you have hills to climb. The mid-mounted motor configuartion maximizes torque to get you up inclines.
E-bikes mostly use motors and battery options from a few major suppliers: Bosch, Yamaha, Shimano, and Brose. A few other brands exist, but are less reliable or powerful. Some, like the Yamaha system, have more torque and others are quieter. But generally all four make good options. Look for motor output (in watts) which will give you an idea of total power. But watt hours (Wh) is perhaps a better figure to use—it takes into account battery output and life to give a truer reflection of power.