It depends on your definition of "better." As for a taste difference, I cannot find a perceivable difference between a recent-vintage screwcap and a recent-vintage cork.
It is better for freshness, as wines with Stelvin closures rarely are corked. It is convenient for those who have trouble using corkscrews or do not have one. It is better for the winemaking process as it is one less natural material to be grown, harvested, and processed.
It is worse for those who fancy the feeling of uncorking a wine, and I have not seen enough research to show how effective these types of closures are for aging wine. It serves to reason that you should be able to age a screwcap wine standing straight up, but whether or not the seal remains airtight over time I do not know, and would not trust. Plus, the wines that are age-worthy usually do not have this closure, so no harm, no foul.