+15 CHA or +15 INT is better?

Let have some introduction first.

I'm Feoh Soultaker. After lv my char to 100, finally, I have some adena to think about putting some dyes to make my char stronger. I read what is introduce in Char's stat window that +INT will increase M.atk and + CHA will increase almost all stat (P.atk,P.def,M.atk,M.def, CP/HP/MP).

Have anyone try comparing +INT and +CHA, what is better?

for mages,

+5 int, +4 cha = the best (+5 int, +5 char = the best of the best but godly expensive)
+5 int, +1 wit = 2nd best
+5 int = 3rd choice, not bad and the most cost effective.

everything else, it's really upto people I guess....

By the way, +5 Cha alone = just garbage.

By the way, +5 Cha alone = just garbage.

This is all that really need be said. It's a great secondary stat because on its own it will do more than the +1 secondary stat (and certainly better than no + stat, and far better than a - stat). But it will not give you anything close to the gains +5 to your classes primary stats will give.

The breakdown above for nukers is basically sound.

Which way you go will depend just how much you are willing to tweak your character. The more you work on it, the more expensive each tweak gets and the less return you get for that investment.