Both cases are top quality and should last for decades, but the die cast zinc original style cases are probably among the most durable current production keyboard cases in existence today, outside of keyboards designed for special situations.   I recommend the original style cases but recognize that the compact cases have their place if you want to travel lighter or want an extra inch or so in bezel savings.  You can buy a spare classic case and switch between compact and regular cases if tastes and needs change in the coming decades.