For me, that would be Secure CRT. I have yet to find a terminal emulator that matches its feature set. If you regularly manage hundreds of machines using various connection protocols (serial and ssh mostly in my case) It’s worth the $$$, and so far there hasn’t been any subscription nonsense. I liked using it at work so much I forked over the dough to have it at home.
None of the free alternatives do everything I need.
I’ll also mention a few iOS apps. One is Sun Surveyor. It’s an AR app that shows you the position of the sun, moon, and galactic center at any given time. The other would have to be Radarscope. It’s a weather radar app, but it’s a really good weather radar app.
I want to be explicit. I’m not at all saying people “shouldn’t be able to profit from their work”. No way; all labor should be rewarded. I’m just saying I can see why works of art are somewhat different than tools. You use fiction versus non-fiction books as an example, but I’m actually putting those in the same box as games and movies.
I generally prefer FOSS for practical and ethical reasons, but I have no problem with paid software or people being paid to write free software. I think most software can be done better by an interested community. Free software is just better in many cases. Sometimes that is true with games too though. Enemy Territory, for example.