Comment by buddylw
I have a Swiss Micros DM42, a modern clone of the HP42s on my desk and I have the plus42/free42 app on pretty much every device I own. Stack based calculators are great because the stack works as a little scratchpad when I'm trying to figure something out.
If I'm solving a problem of any complexity I'll move to a more appropriate tool like python or a spreadsheet, but for the simple math that needs to be done around the edges personally and professionally, I like a calculator. If I'm at my desk, I'll use the physical version.
I have one on my desk at work. I use it 2-3 times a week for quickly calculating things. It gives me a good feeling every time I use it.