It's not a question of either a better lens, or post-processing. Both are required. With a lesser lens, more post-processing will be required to come close to the same result (and more processing may increase things like noise).
The issue is that the lens resolution that is lost cannot be recovered, and contrast is closely related to resolution. In addition to uncorrected lens aberrations that reduce contrast, lens glare will destroy microcontrast and hence resolution (because micro-detail has low contrast to begin with and may be drowned in the noise floor). So not only will we lose resolution and the possibility to recover some of it with post-processing, the overall image will look duller than it would do with a better lens.
Lens design is the first step in reducing the number of air/lens surfaces, because at each transition, some 0.5-1% of the light will scatter into non-imageforming glare, and that is with well coated lenses (non-coated lenses can lose some 2.5% at each air/lens surface). The design of the inner surfaces of the lensbarrel, and focusing gears, blackening of lens edges, and designing kitted lens groups instead of loose elements, all contribute to a better image.
Let us also not forget the Lens shade/hood and a clean front (and rear) lens surface. A zoom lens may have to compromise as to the depth of the lens hood. At a longer focal length a deeper version can be used, while at a shorter focal length/wider angle of view, a shallower version is required. Some designs use a front element that retracts deeper into the hood at longer focal length settings.
I have no information about the specific lenses that the OP mentioned, so I cannot advise on that. There are probably brand specific lens comparison sites and fora that may assist.
Additionally, the mentioned software solutions can come a long way in turning a mediocre image quality into something more useful, and very good image quality into something stellar. In both cases the images will benefit, a lot.
Thank you so much for taking the time to offer the foregoing. Well intentioned explanations are often beyond the pale for those of us not versed in scientific esoterica. I am actually able to understand and certainly appreciate your what you have said. I am guessing you might be an educator.