Under both our insurance plans (we work for the same employer), we can order Ameda bags free every 3 months. We have also tried most every other bag on the market. We'll be reviewing them for you, covering everything from price, to toughness, to ease of use. Depending on your personal preferences, you might choose a different bag as your favorite than ours. For price, we'll use Amazon.com to compare (except for Target brand); however, you may find better prices elsewhere. All the bags we tested are 100% BPA free. We both pump directly into bottles, so we were not as concerned with the measurement marks or the ability to pump directly into the bags as other mamas may be. 
I found the measurements highly inaccurate and we both like to freeze the milk flat anyway. Medela and Ameda bags both have the holes at the top to pump directly into them. Most bags can store 6-8 oz, but the Ameda and Medela bags are smaller, storing only up to 5 oz. These bags can stand up on their own for pouring, which I don't use, but is an important feature to Jen.
THE RESULTS...
1st Place (Best Bag): Dr. Brown's
The Dr. Brown's bags are the closest we found to perfect. Thick, smooth plastic, with double sealed zippers and a tamper proof sanitary tear-off strip. The zipper is nice and wide, the writing tab open with a white background. These bags have a contoured top for pouring. They don't "stand up" on their own perfectly. They are one of the more expensive brands at 28 cents per bag. Overall, these are the best bags we tried.
Best Overall Value & Quality: Target's Up & Up
The Target Brand Up & Up bags are a very close second in quality, and they are actually the least expensive bags on the market. Other than the material being slightly stiffer, they have all the great features including thick plastic, wide double zipper, sanitary tear-off, high storage capacity, contoured top for pouring, and a decent writing tab (although reverse/upside-down labels). They also don't stand up on their own superbly. Best feature - these bags cost only 15.5 cents each! That's half the price of the more expense bags!
Recommended Bags:
NUK
Overall, The NUK bags are a solid choice. Smooth, thick plastic that hasn't leaked for Jen or I. Double zipper, and holds a good amount, and a pretty affordable price. The con of the NUK bags is that they don't each have a tamper proof tear-off. I'm also picky about the place where you write the description of the contents. I like it to have a background so the writing shows up. I also like to be able to write on it with any pen, and not have to use a Sharpie. The NUK bag is clear, so you have to use a dark colored Sharpie.
Ameda
Jen really likes the Ameda bags because they stand up on their own very well when pouring milk into them. They are strong and neither of us have had them leak. They are expensive, however, unless your insurance covers them, and they only hold 5 ounces and have a narrow zipper.
Not Recommended:
Honeysuckle
I actually liked the Honeysuckle bags and never had any problems with them, but Jen had leaks. The feature that matters the most to me in a bag is the width of the zipper. Because I only have one hand, pouring can me difficult. I like a bag with a wider zipper, because I can turn the top of it inside out and place it over the neck of the bottle to dump the milk in. This prevents any milk from getting in the zipper. And it's super easy with one hand! Because of this, the plastic material also makes a difference. The smooth bags are easier to turn inside out and back after the milk is in them. The Honeysuckle bag does well on these counts, but if it leaks, none of these features matter. Another downside is that it's hard to feel if the zipper is properly sealed.
Medela
When it comes to the labels on breastmilk storage bags, I like the text (amount, date, etc) to be right side up. I am annoyed by bags with several text spots; I particularly hate the tabs with "name" as a category on them. Medela has the best writing tab - white background and no labels - you write what you want, how you want, in any direction you want. These bags are strong, stand up relatively well, but are small with a narrow zipper. They don't freeze flat as nicely as the bigger bags.
Lansinoh
There are two things I love about Lansinoh bags: they are smooth and easy to turn the top inside out, and the double zipper CLICKS and you can both hear and feel that it's secure. So I loved everything about these bags, until my husband started thawing the milk frozen flat in these. The side seams leaked. Horribly. Such a shame.
AVENT
Jen did not have as much of a problem with these bags as I did. They are really pretty bags, just aesthetically pleasing. They stand up on their own great. They have two tear-offs, the first one for sanitary/tamper-proof purposes, and the second to use when you want to pour the milk out and use it. The zipper and bag is very narrow, and you can tell the sides are very secure. The writing tab is huge, but you have to get the milk through that tab, past the zipper and into the bag, which for me was nothing but a huge mess. I spilled milk and every time had to shove a paper towel down in there to dry off the zipper before sealing. So frustrating!
Comparison Chart
Brand
|
Cents/bag
|
Width
(in)
|
Zipper
|
Pour Spout
|
Label
|
Sanitary Tear-off
|
Material
|
Capacity
(oz)
|
Up & Up
|
15.5
|
5
|
Double
|
Yes
|
White
Reverse
|
Yes
|
Thick
Smooth
|
6+
|
Lansinoh
|
15.43
|
5.1
|
Double
Clicks
|
Yes
|
White
Reverse
|
Yes
|
Thin
Smooth
|
6+
|
AVENT
|
17.04
|
4.5
|
Double
|
No
|
White
Reverse
Large
|
Yes
|
Thick
Stiff
Crinkly
|
6+
|
Honeysuckle
|
19.8
|
5
|
Double
|
Yes
|
Yellow
Upright
|
Yes
|
Thick
Smooth
Stiff
|
6+
|
Nuk
|
17.94
|
5
|
Double
|
Yes
|
Clear
|
No
|
Thick
Smooth
|
6+
|
Dr. Brown's
|
28.0
|
5
|
Double
|
White
Upright
|
Yes
|
Thick
Smooth
|
6+
|
|
Ameda
|
31.25
|
4.1
|
Single
|
Yes
|
White
Upright
|
No
|
Thick
Crinkly
|
5
|
Medela
|
32.72
|
4.5
|
Single
|
No
|
White
Blank
|
No
|
Thick
Smooth
|
