Well it also may be the key layout. After years of using a certain HP calculator, you get used to the layout. I prefer the 32Sii. Some have primary keys for x^2, x<y, 1/x, PI, etc. if I designed my own I’d have 10^x and LOG(x) as primaries. All depends on what field one works in.
But there is a large degree of throwback HP fanboyism.