honestly web programs, you can't beat stuff with hard core diagrams, text boxes, etc. I keep those view tickers running on the engineering calculator websites.
I.e.
https://hamwaves.com/inductance/en/index.html#inputYou get a 20+ entry calculator and effectively MAN pages. There are some advanced useful suites for graphing calculators but honestly most places now.. the electronics lab is loaded with internet enabled computers. And the graphics on the websites help keep other engineers aligned.
If it had to be offline I would get a tablet with the websites saved on it, if possible. The heat sink designer programs some websites have are wonderful too, but its processed on their end through CAD sim so you NEED the connection and their servers to be up.
And since I often have many numbers to fill in parametric equations? if you can call it that, excel is the calculator of choice over a graphing calc because simply put the color/resize/etc functions of excel make it more clear and presentable and sharable.
What I would want though is a magic notebook that has the different pages that look like blank physical paper worksheets, so you flip to the correct page and pencil stuff in, then the answers appears, but it has the same consistency, weight, feel, etc.. of actual paper that I can bend the edges of and stick physical indexing marks into and so forth. But I suppose you need Merlin for that?