I have a Medela Pump in Style and a Lansinoh electric. The Medela is awesome and designed to be compact and portable. The Lansinoh was almost half the price and was as good a pump, but didn't come with the fancy bag. Both have battery-power options, but you're never going to get the same power that way. If you're going to possibly have more children and/or will be pumping on the go a lot, go ahead and spring for the Medela.
Otherwise, the Lansinoh is quite fine.
Oh, the Lansinoh's suction system also does not have the possibility of contamination that the pump in style does. If you can find a used Lansinoh and get new tubing and such, there's no issue.