Just decide what kind of character you want your MC to be and level you stats accordingly. For example if you want to play a more tanky character just lever str and endurance or if you want to be more magic focused then level int and magic.
There is little reason to choose to bump your magic stats up though; your main doesn't learn any magic skills. Nemissa on the other hand learn tons of useful magic so it is a great choice for her. To decide what you wanna up for your main; END and LUC are always useful, AGI at 23 or 24 is enough to outrun just about any enemy; STR is best if you mostly strike with swords but is not taken into account when calculating gun damage so if you'd rather play with guns you don't need any.