I used the Ameda Purely Yours, went through two motors but I was doing long pumping sessions, 30-40 minutes.
I used it at work , wasnt too hard to cart around, was a bit too noisy to talk on the phone with - I could hear people ok, but they could hear the pump, too. It had a battery option but I never used it, too expensive, I did use the car adaptor & that was very handy, cost me $40 and I used it quite a few times. That was EE though... you probably wouldn't need it just for work.
I guess you would be looking at cost, how long you plan to BF for, resale value (I think both are quite good), portability & power options.
I didn't know the Medela had a re-chargable battery...that's cool
I also pumped hands free, BEST thing ever.