Of all the brands, I choose Casio because it is a well known and trusted brand. It has all the features for Science and Mathematics functions and all in all it has 249 functions which includes 164 scientific functions and that includes statistics functions too, so it it more than enough for my scientific and mathematical calculations.
Pros: The calculator is easy to use with clear instructions manual. It has solar power and comes with batteries too so there is no need for me to worry that it will run out of power during my examinations. It comes with a case to protect the calculator from water spills. The case is very smooth and easy to slide open. The calculator has a dimension of 84X155X12 mm, hence it is very light and easy to carry about. It has large keys which make it very easy to press and the writings on the keys are big and clear too.
Cons: None that I can think of.