I tried Madela and Avent before discovering the Lansinoh pads, and Lansinoh is my favorite by far!!!
The Madela pads are shaped similarly, but are slightly smaller and thicker. They didn't lay flat, and gave a lumpy appearance under clothes. The Avent pads are even smaller and thicker, and despite their thickness, I had problems with leaking straight through! I couldn't even finish the box of Avent pads because my husband kept making fun of the way they looked under clothes. There was no way I could wear them out in public with a straight face. They don't stay in place well enough to wear to bed- so totally useless!
The Lansinoh pads are super comfortable, full coverage, and leak proof (for me at least). They have a sticker to hold them in place, but I don't even need to use it. The backs are so smooth that they are totally incognito under clothes. You can get them here!
Now that I'm smooth, I'm off to find a nursing bra with enough support!