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.
For many bikes, battery range is more important that total power (because they're all pretty powerful). You want a bike that delivers a range long enough for your rides at the power levels you want. Most e-bikes will have three to five levels of assist kicking in anywhere from 25 percent of you pedal power to 200 percent boost. Consider how fast the battery takes to recharge, especially if you'll be using your bike for long commutes.