I am looking for the best in-ear noise canceling headphones for my Droid.
I am looking for an under $25 pair
I'm sorry, but the reality is those two statements contradict each other.
What you seem to be looking for is a listening device that reduces background noise. There are three ways to achieve this-isolation, active noise cancellation or a combination of the two.
Isolation will block the sound. In a headphone, this will involve a "closed" design that will completely cover your ear and are generally going to be relatively bulky. Looking at studio quality headphones, and you will get a sense of the design, recommended brands would be Sony, Sennheiser, Audio Technica and AKG. Please note that there are "semi-open" designs that are designed to let in some ambient sound, so make sure you look for a fully closed design. These normally sound great, but as I say, are bulky.
For isolation in earbuds, you want something that inserts into the ear canal, ideally with a "plunger" design. Higher-end, IEM-based models will allow custom molds to be used. Sound quality, comfort and isolation with those is outstanding, but this can get really spendy and is way above what you say your budget is. I do not have personal experience with them, but the SkullCandy buds have gotten good reviews (here and in other places) and would probably fit your needs.
Active noise cancellation uses a microphone to sample the ambient sound, then active electronics to invert the phase and inject that signal into the transducers. The algorithms used can vary in quality, and the inherent nature of the technology causes the noise canceling to become less effective at higher frequencies. Because of that, the best systems will use a combination of isolation and cancellation.
People like the Bose because they combine good active cancelation with isolation and they are comfortable. My personal opinion is that they do not sound that great and they are overpriced for what they are, but for those who have posted saying they like them, more power to you.
Personally, I travel with a pair of Audio Technica noise canceling ear buds that work quite well and sound good. My only quibble is that they can start to get uncomfortable after about 5 hours on a plane.
So, for longer flights, I use Sennheiser PCX250 headphones. These have limited isolation, but very good cancelation algorithms, sound good, are comfortable and are compact.
I leave my high-end Sennheiser headphones and Etymotic earbuds at home when I travel-the Sennehisers are too bulky for travel and both are too expensive to be sacrificed to the Laws of Murphy that seem to stalk me (and my bags) when I travel.