I haven't watched Yu Yu Hakusho and I don't really want to either. I just know it couldn't be anywhere near as good as Hunter x Hunter ... I doubt Togashi did anything but improve with the new series he made.
Hunter x Hunter for SURE!! I like Yu Yu Hakusho (The manga is better though XD) but Hunter x Hunter is just way too amazing!
Yu Yu Hakusho is the superior show. There's a reason why it's far more famous than Hunter X Hunter. With that said, I enjoyed both shows, and I loved how YYH characters would make cameos in Hunter like when Suzaku's featured in that book of that villain who captures his enemies powers and keeps them inside the book.
Yu Yu Hakusho, solely because I could never get into Hunter X Hunter, while Yu Yu was always smooth sailing for me. Yu Yu is just a classic.
I've never watched Yu Yu Hakusho, but I have read some of the manga and I really enjoyed it. I absolutely adore Hunter x Hunter. Hnnnng, can't make an official decree on this one. Not enough data.