I never said engine is everything in a car, But engine is one major thing while buying a car, as its directly related to, speed, fuel consumption, noise, maintenance and many other factors.
Body dimensions, style, thick or thin wheels, dynamics, shape, all these are personal preference, and if you want to the best, leave Suzuki altogether and buy Toyata or Honda for instance. Why we are opting for Suzuki is our price point/budget.
If your money has value to you, any Wagon R owner won't loose anything, other than style and looks i feel. Suspension can be fine on both and if according to you Cultus will have advantage you need very sensitive ASS to feel that.
For an average user. i find there WR can do just fine, and for car lovers, for those stuff like design, dimensions matters a lot, they may shed 1.5 to 3 lacs more on Cultus, i thought only point of buying Cultus if it was Auto and not manual.
Lets see how Cultus will perform. I feel it will be its price cut, like WR had to promote it. My humble opinion.