let's make things clear: Classic is basicly what GoD should have become if they kept all the classes variety, the main major changes are some skills after 2nd/3rd class, and how character stats work. the world is the same as c1-c2, so far.
Hi5 is just an older chronicle. with more content probably, but a terrible, horrible, disgusting class balance. i still remember every warrior at lv84 running around with rush impact, it was really a joke of a chronicle.
if i had to choose while starting from scratches, i would rather play Interlude or eventually Gracia than Hi5, but that's just me.
beside, after playing classic for about a year, there's no way i'm going to throw away all that time to restart from 0 on another chronicle, simply because i don't have the will nor the time to farm again for all the levels, gear, SA, knight eppaulettes, elemental stones and god knows what else.
not worth the effort, so i'll keep playing here.