Me too, I completed the license board for each character and made sure to give an equal number of Espers to my main characters, so they all ended up with 4 espers, except Vaan who had 4+Zodiark.
I didn't specialized my characters in anything, I used them in different strategies as the different situations required ;)
OH, since you're japanese, did you get to play FFXII: Zodiac Job System?
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
