At -2.5, you probably don't get much shrinkage or aberration with your glasses, so they work better for you. For me, at -4 plus strong astigmatism, wearing glasses makes everything look tiny, and circles look like ovals... contacts are a better experience. That said I have tried over a dozen types of contacts over the years and it took me many many attempts to find both a product and a set of lens parameters that worked well enough for my eyes to want to switch from specs. Now I found that, I don't even own spectacles any more.