Just my opinion, but Thunder is very lacking in debuffs and healers atm
and this element is kinda expensive to main because most of the good thunder himes are either SSR (Mammon) or limited edition (Thunder Aphrodite is a thunder healer but limited, there's also SR Thunder Nyarlathotep for C frame debuffs but she's also limited)
Not to mention you'd have to wait awhile before they get released here on our version
Thunder did get a good non limited SSR healer recently on DMM, but like I said, you're gonna wait till next year for her to even come here..