I can't believe someone above wrote that the Slash is junk!? Totally totally false! If you read here, and also if you ask around, 99.9% will tell you that the slash is the most durable out of all of them. Look on youtube for the video of the dude that fished his out of a frozen lake, and then drove it off the ice. There's another guy that takes his Slash out of the box, and drove it into a pool, then drove it back out- they're pretty bullet-proof!
I think they are all good trucks (Associated SC10, HPI Blitz, Losi Strike, Traxxas Slash) If I were you, I'd think about how much racing is gonna be a factor. There are VERY active Traxxas Slash-only (box-stock trucks only) racing classes where I am. This is a great way to get into cost-controlled racing. If you are gonna do mod racing, and you're prepared to spend $$$$ on a brushless system, lipos, and hop-ups, then maybe you want to consider the Blitz or the SC10.