I own both and like both. This is not a real comparison as the games are very different -- Mid/Late Stern SAM vs very early WPC, different world of technology, themes, rules, and designers. Which one do I like more? Depends on the day. Some days it is WPC only, other days I feel like Stern only. You know what kind of game you like and it is pretty easy to find both to play so what do you like?
As far as cost goes -- XMLE is underrated (low for what you get) and FH is overrated (high for what you get). But, if you want a FH, you pay the price.
Of course, "Hey Bucko!" always makes me laugh as new players often think it said something else.