Okay, here is my top 3. I am excluding the Catalyst because it is fairly new. But anyway, here it is (note that these always change)
1. Valentines Day - On my first listen to MtM, this one stood out the most to me. The melody was so catchy and dark and at the end when the verse part is brought back in..it..it.. it's just awesome.
2. New Divide- When this song came out last year, I just kept listening to it over and over again and it became one of my favorites. Within the first week it already had over 200 listens on my Ipod! And I still haven't gotten sick of it, well I did for awhile but now I like it again =D.
3. With You- Originally I HATED this song with a passion. but eventually it started to go on me. I love Mikes verses in this and the delay effect on his vocals.