I used the Avent pump for DS1, and for DS2 decided to go electric. I started with the Medela Mini-electric and also found it too noisy. MEdela just came our with a new one call the Medela Swing . It is really quite and can run on batteries or AC and can fit on a belt (handy if you are in the middle of pumping and DS1 wakes from his nap early!!). On its strongest setting it is a bit noisy, but I put a pillow of it and I can still hear the TV.
Hope this helps,