I would definitely suggest the launchpad. I own a ridiculous amount of MIDI controllers, expensive, elaborate, and simple ones and I have to say that my Launchpad is used most out all of them. That said, it does not automatically map to the 8 macro knobs the way you want it to, but there are numerous midi remote scripts that will do it.
I use this one.http://motscousus.com/stuff/2011-07_Novation_Launchpad_Ableton_Live_Scripts/
The above script turns the launchpad into a full scale controller for live. Device control, step sequencing, macro(blue hand) is what your interested in, and much more.
Theres also the native kontrol scripts that are AMAZING!!! LPC is $30 but worth every penny! They even have PUSH emulations.http://www.nativekontrol.com/LPC-Live.html
In case your wondering the rows of buttons can control knobs in the soft-ware.
I love my launchpad and if it ever broke I would instantly buy another one. It is in-valuable.
But like I said above^^^ There are scripts for the lpd8 and most other mainstream controllers to give the functionality you want.