Casio is the best, but only if you buy the real thing. Fx-82ES and 99 1ES are both good. Fx-82ES is cheaper and uses batteries. Compared with fx-82ES, 99 1ES has more complete functions, can solve equations, and adopts the dual power supply mode of battery and solar energy, which is slightly more expensive.

Introduction to Casio fx-82ES Baidu Encyclopedia /view/ 1963224.html

Casio 99 1ES Introduction to Baidu Encyclopedia /view/ 1974879.htm

I hope the above answers are helpful to you. I wish you a satisfactory calculator as soon as possible.