I recently got the Jawbone Up and so far, I really like it. Takes getting used to wearing it, but man, the silent alarm is SO much better than your typical phone/alarm clock. You don't wake up with the "OH DEAR GOD TURN IT OFF", but more of a "oh hey, it's morning, I can get up". It's also water proof, which my old Fitbit, isn't.
I did get my wife the Fitbit one, that one is water proof and also has a silent alarm.
One plus I like about the Up vs. the Fitbit, you don't have to worry about losing it or moving it if you change clothes nor do you have to put on a band and move it again to track sleep. Just seems a lot more seemless.
Edit - I will add, I think the perfect device would be the Up, that had a display showing your steps that could sync wirelessly or through Bluetooth. The Fitbit one can sync with BT and has the display, but I just prefer having it on your wrist and not worrying about losing it or changing to the band to wear for sleep.