What car would be better for driving?

Jetta is the most safe, gets the most gas mileage by far, and if you get a V6 or V8 you can go pretty damn fast

Depending on the model, and I'm assuming you're not talking about the highly-tuned Lancer EVO, the Jetta will be more powerful for climbing hills. However, for the past few years the Jettas has also been plagued with a variety of expensive-to-fix electrical problems. I used to be quite a fan of most VW product, but of late they seem to have abandoned their commitment to reliability. Mitsubishi, on the other hand, is producing some very reliable cars. However, if you are trying to compare apples to apples, the Galant is more a match for the Jetta than is the Lancer.

Other cars in the range you are looking at that are reasonably good hill-climbers are the Subaru Impreza, and the Ford Fusion, both with good reliability records.

climbing needs torque

lancer wins big

(lancer 300lb vs jetta 207lb)

mpg : jetta wins big

(jetta 22city/33hwy vs lancer 17city/23hwy)

jetta's torque maybe is already a big enough improvement from cobalt depending on which cobalt version