"high-end" is a sort of misnomer when applied to burger joints.
Fuddruckers is priced slightly higher than fast-fast-food places and is in a sort of small niche with johnny rockets, red robin, and maybe something like becks prime which is a local chain. fuddruckers is the best of this lot

of the standard fast food burger places in-n-out is imo tops. (it is regional chain, however). whataburger is also very good. i prefer both of these to all of the above

as with most foods the best belong to independent local restaurants, either cheap "dive" bars or shacks or in fancier "gourmet" places (10-15-20$ burgers). for instance in austin texas one could list casino el camino, burgertex, fran/dan, huts, hyde park.