I think it depends how much you will use it/milk you need. I have borrowed the Ameda one and it was fab, it worked well and I could express a good deal of milk (I think of if it as in 'industrial' breast pump) pumping both breasts together saves time. I don't know if they've changed it but some parts can't be sterilised in microwave/steamer but have to be boiled/Milton.
I've also used the Medela that was also good and easy to use.
I would say for occasional or daily use Medela was great, if you want to pump and save loads of milk the Ameda is worth it.