Just the regular level up and learn skills system is fine for me. But if they tweaked the VIII junction system, so that you didn't have to spend a long time drawing magic/collecting items for magic, then that would be good as well.
Buying skills and levelling up for stats.
Levelling up for skills and stats.
Job/Dressphere System for skills and slight stats adjustment with levelling still necessary.
Learning skills from Espers/equipment, and levelling for stats.
Materia system for skills and sligh stats adjustment, while levelling still adds stats.
Drawing magic and the Junction System for the main sorce of stats building.
Sphere Grid for skills and stats.
Just the regular level up and learn skills system is fine for me. But if they tweaked the VIII junction system, so that you didn't have to spend a long time drawing magic/collecting items for magic, then that would be good as well.