What are the key things to look for while choosing a breast pump?

1. Portability If you're using it mostly at home or in the office, you can consider a hospital grade breastpump. it's bulkier, but it does the job better. I'm using Spectra S1. If you need a breastpump which can be placed in your bag, get Spectra 9+ or Medela Freestyle. 2. Noise level Whether it's in the dead of the night or in the office, it's better to have a pump which is not that noisy. Spectra S1 performs well in this aspect. Avent pumps are really noisy. 3. Budget Of course, your budget matters. I purchased my pumps from Qoo10 and it's a lot cheaper compared to those with local warranty. Product wise, it's exactly the same thing.

It depends on your lifestyle as well. This was the first thing I was asked when I was looking at pumps. If you'll be home most of the time, you can opt for heavier, more powerful pumps. If you foresee that you'll be pumping out of the home and will be traveling often, get a portable one. If your lifestyle affords it, getting a manual pump is the cheapest option! It's also wise to check which brand has parts that are easiest to source locally in case you need to get extras or parts get broken.

Cost,portability (option of battery operated if no ac power if outside home), size, ease of assembly and dismantling and whether can change from 2 pump to 1 pump and vice versa at ease.

This would be a good read with regards to your question. http://sg.theasianparent.com/buying-the-perfect-breast-pump/

thanks