It's also not necessarily an either or. I have a pair of Etymotics 6i I use for all sorts of travel. Space wise they are hard to beat. (though I wish they had a shorter cable (since they are never connected to something farther away than my pocket or my hand). I also routinely borrow my significant other's Audio Technica over the ear active noise cancelling headphones.

When I want maximum noise cancelling and sound I wear both. When I want to sleep without music, I wear regular foam earplugs with the Audio Technica headphones. When I want to travel light (or am on public transit, like a subway or bus, or we are both travelling), I wear just the Etymotics.

Granted, my combined set up exceeds your budget, but you could consider both. When I had to chose one, I decided the compactness, portability, and broader use of the in ear ones were a better value for me. But then again, I don't mind sticking something in my ear (though it did take some learning to get a good seal.)