QFN VS MSOP- Which is better for thermal performance
Which is better for thermal performance[?]


\$\theta_{JC}\$ and \$\theta_{JA}\$ values are given in the "Pin Configuration" drawings on page 2 of the datasheet. 

The QFN package has lower values.

From your comment


  What else can I do from the PCB design standpoint to augument the thermal performance


To minimize \$\theta_{JA}\$, you can 


provide multiple vias from the exposed pad to ground planes
use heavy copper on the ground planes
add ground fill on top and bottom layer (and connect it well to your hot chip and the buried planes)
Provide forced air movement over the board
Arrange chips so that hot chips are nearest the source of air flow, and air doesn't flow over one hot chip to another one
...