I've not any personal experience with the two options, but I've read reviews and the usual trend is that the Swans are the better option. They are also incredibly flat down to 60hz whereas the audioengines are colored with generous mid-bass bumps. Mid-bass bumps are acceptable in headphones because of their lack of omnipresence, but for speakers it only muddies the sound.
I like larger speakers and put them on stands. Can get the same performance at lower cost. A lot depends on the geometry of your setup, how far the speakers are from the walls and if they are low on a desktop or raised up. In fact this stuff matters more than which brand of speaker you buy.