The high ATA of hucaseal is sure a really good thing.
I would personally consider things like that :
If you're playing all alone, no dual log -> choose Hunewearl
If you're playing with people or you can/want dual log -> choose hucaseal (notice: dual log is actually not a good point, for it's a pain in the ass to handle and you'd better just play with people or just with one character at the time. Or perhaps am just not good with the stress of having two characters ^^)
The reasons :
Hunewearl : have shifta/deband up to lv 20 AND jellen/zalure up to lv 20. This is really great when you're solo, because when applying buff/debuff, you can handle everything by yourself (most of time of course) with average stuff. Moreover, you got resta which is very useful to avoid piping to town every time you run out of dimate/trimate
Hucaseal : have more ATP, have more ATA... and have TRAPS which is overgreat. So if you can have a hunewearl or a FO to heal you and more importantly to buff you and debuff monster... Hucaseal is actually a better choice than Hunewearl in that case.
Was my two cents, and it's very discutable but I think you got the main points. (Then there is the skin or appearance, and the weapon animations/restrictions of course.) At the end it's all about your personal tastes ^^