I much prefer immediate execution or RPN, none of this new fangled VPAM nonsense! It’s a personal choice of course, biased by what I was brought up with.
As for a programmable calculator, if I’m going to do programming, I’ll do it on the computer. For me, a calculator is for getting small, quick back of the envelope calculations.
Back in the 70s, programmable calculators were a real wonder, I had several. Practically speaking, I have no use for them now, other than for personal interest’s sake and a bit of good old fashioned nostalgia.
The HP Prime for example is an amazing bit of kit, but to be proficient at using it takes very many hours. As an experiment I did do some fairly heavy vector maths on it a couple of years ago, seeing how I got on with it as an alternative to Octave or Matlab. While it certainly worked in this practical use case, I found its biggest drawback is the keyboard entry, not being QWERTY (not to mention a terrible colour choice for the secondary key functions, rendering them unreadable for my old eyeballs). It’s actually easier to use the PC emulator for the HP Prime, but as you’re using a PC, you might as well open up Excel, Octave, or your favourite IDE and hack something together there.
I just use the tool I find most convenient for the job. Personally, I find using Windows’ calculator to be frustrating tomuse in comparison to a desk calculator. I also find calculators on smartphones to be less than optimal, probably due to the lack of tactile feedback from the touchscreen when you’re keying in stuff quickly. That said, if I were to select my favourite useful calculator app it’s HP’s own HP 15C app. Their HP Prime app is pretty good too, but you’ll need to be prepared to spend quality time learning how to use it, and frankly as I mentioned earlier, practically speaking you’re almost certainly better off doing stuff you’d do on an HP Prime on a PC.