I always use store-bought dried breadcrumbs for schnitzel. While I use Panko for other breading, I never use it for schnitzel, because classic, authentic schnitzel is made with breadcrumbs. Fresh breadcrumbs will not work at all and I feel like homemade dried breadcrumbs are likely to be both not dry enough or not uniformly fine enough for great schnitzel. Store-bought, plain dried breadcrumbs are what I generally use, and I season them myself with seasoning salt. Seasoned breadcrumbs will also work. As they are already seasoned, you can skip any additional seasoning. Avoid Italian seasoned breadcrumbs however, as they are seasoned with special herbs and spices best suited for Italian dishes and not schnitzel.