Well, I'm not particularly crazy about either, but out of those two its Sword Art Online by a mile. The story is pretty interesting and made me want more of it. I was more interested in the SAO light novels than I ever was the anime, which I bailed on due to the fact that A) the anime had an awkward beginning with all the side stories and B) the books tell the story in greater detail, with more explanation about the specifics of the game and how it functioned. They couldn't really include that in the anime since having Kirito explain game mechanics to nobody in particular would be weird, but the anime did a good job of making me want to read the novel so thats enough to say that I liked it.
BTOOOM!, oh god... When I wrote up my season outlook on an anime website I frequent I didn't even have to think before that show was firmly placed under the 'TRASH' heading, the first episode having been deleted from my hard disk not long after viewing it so that I could use that space for something more intelligent and productive, like images of cats with funny words on them. I HATED the show, which is rare for me, for various reasons.
For example, an FPS with only explosives and no direct killing capacity is a stupid idea. The main character is a moron (seriously, he's supposed to be all pro at this game and yet he dosent figure out the fact that an explosive has a timer might mean that its a timed explosive until about 10 minutes after the audience did). The director failed to build any kind of suspense. Gore was used in place of any decent writing to hook viewers...need I go on.