The two cars stand for different things, the Optra Magnum is a VFM car, and Chevrolet is being used by GM as a VFM brand, while the Laura (the international Octavia replacement) is positioned as a premium car, with premium charged for its high levels of quality.
So, the decision to be made is 'What do you really want?'. Do you want more bang for your buck? Or do you want a premium (unfortunately Skoda is premium in India) vehicle of top notch quality?
My advice - the Magnum, 'coz I'm a big miser! [
]