I used an avent for one year and really liked it, never had a problem! I mean, as much as you can like a pump :/. The soft shields were actually weird though - comfy but hindered production, and milk would get trapped between the shield and the flange, not what you want while pumping at work! I liked the wide mouth on the avent bottles.
Ive never used another pump so i can't really compare the settings but the avent is completely customizable - you set it based on a few squeezes not a preset. So i think that was a helpful feature esp toward the end when i was doing anything i could to maintain.
'ing with DH since 05/05
DD 01/11 and two long doggies