I've only used and heard rave reviews about Medela's Pump In Style. I've purchased and was gifted the original and the backpack version. Both come in sleek well constructed black bags and include an ac adaptor plug, batteries, 4 bottles, a couple of bottle stands and all the other bells and whistles that make the thing go. Both retail for about $300 a pop.
On the latter version I purchased for my second child almost 4 years ago, there were adjustment nobs to control the strength of the suctioning. Some moms with difficulty lactating have said they get better flow from a stronger suction while others prefer a lighter suction because they get sore nipples easily.
These days, many hospitals rent pumps for use for between $3-20+ dollars a day depending on the hospital, region of the country and insurance plan. Ameda makes the hospital grade commonly used in many hospitals.
Medela also makes a manual pump that I've heard is pretty good, but I used with great success the Avent Isis. These days, they sell them with a storage back that looks like a lunch kit. This was great when I had to travel for business and wanted and NEEDED to express milk out. If it was a short trip, the milk may have been salvagable. The manual pump is also good for short overnight or on the road with the baby when a bulky electric pump may not be practical.