I have the Avent double electric pump. It was recomended over the Madela by my local lactation store and I love it... as well as one can love a machine strapped to your chest making hee-haw sounds and pulling liquid gold out of your chest! lol. I've only been using it at home (going back to work next week). The lactation store said it has 2 separate mechanisms inside for the 2 pumps, making it more durable and stronger than other leading pumps. It is not uncomfortable (except for my dignity) because it has extra soft plastic massaging pads (they call them petals I believe) inside the part that goes on your breasts. It also has a hand pump that is used to set the pumping up; you pull the handle at the rate and force that you want and press a button to automate it. If you want it to pump at the same rate each time, it "remembers" the setting from the last time you pumped, even if you've turned it off. Also, it comes with a 2 year warranty and one of the plastic tubes had a slit in it (not sure how it happened) and they sent me out a new tube immediately, no questions asked! I was really impressed with the customer service.
I also recommend getting a "hands-free" pumping bra. It sounded silly to me at first, and the picture on the Madela box of a woman emailing while she's pumping is a little extreme (no, I'm not pumping right now), but I'm glad I got one. I can relax a little while I pump, not having to hold the bottles on. It did not come with my pump but I got one at Motherhood Maternity.
I have not used other pumps though, so I can't compare. Hope this helps.