To simply max, I would say Charisma as it totally bores me out, even though I haven't tried horseriding yet since it seems unappealing to me.
As for supermaxing, they all get hard and it depends how you play.If you don't have items saved up handiness is a pain, however inventing can be troublesome as it isn't a sure shot. Writing without the moodlet manager really is boring since masterpieces take so long to complete(if you're aiming high at specializing on them, that is.) However on the scale of boringness I would say logic. Tutoring people is a long, painful thing to do.