Hi there I started out with an Avent Isis manual, I found it adequate for occasional expressing. I guess it would differ from person to person but I found I could only get a decent amount out in the morning when I was really full. If I need some EBM, I'd give DS his first feed of the day from one breast then express off the other. If I needed to express more later in the day I'd have to feed him off one breast all day to let the other get full enough to express.

It's pretty simple to use and clean (there are a few small parts though, the valve can be easy to lose!) I found I could do a few quick pumps of the lever to get the milk to let down then I could just hold the lever still half way and the milk would flow easily without me having to pump, if that makes sense? You just have to make sure you hold it on your breast pretty firmly as the suction tends to release pretty easily.
I've now moved on to an electric pump as I need to express more often but the Avent served me well for those occasional epxresses.