I'm using AVENT by Phillips. So far I've got no complains. I did not test other brands though. I'm using the duo electric breast pumps. it also comes with manual handle to pump milk manually which i usually use when i have to stay out for long. It's good to buy duo pumps as it really cut time by half.
I went to antenatal class with Thomson Medical Centre. The instructor mentioned that not all breast pumps suit all mums due to nipple size differences, suitability of the strength of the pump, etc. So she suggested going down to Thomson Medical Center parentcraft to test out the different pumps they have there before buying. If budget is not a constrain, dont't simply choose the cheapest but the most comfortable one.
You can also visit motherhood or parenting fairs to take a look and try the breast pumps. i got a very good offer during last yr's motherhood fair in june for avent breast pumps. there's lucky dip and free diaper bag which is of very good quality. i got about 4 125ml milk bottles, nipple protector, 3 pairs of pacifiers, breasts shell, moisturiser for baby, moisturiser to reduce stretch marks and lots of others for the lucky dip. I think every $50 spend is 1 dip. The pump is expensive at around $800 i think. can't really remember. I think fairs have good promotion and prices so do check them out.