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 bought Alibre Design, as it was a less oppressive situation license-wise, but these days I find I’m using it less than I might supply because I prefer staying in Linux for literally anything else. It was a bit pricy, but at least it was a perpetual license. I am hearing that while they don’t intend to support Linux, they’re moving away from some of the libraries that have prevented Proton from working.
The rest are varying degrees of oppressive lock-in and feature erosion. PTC/OnShape in particular has a huge “Fuck-You” attitude towards anybody who wants to consider throwing a design up on Etsy or selling a few trinkets without paying out the ass for a professional-grade subscription, and being the only fully mature web-based tool, it’s the only one that works properly in Linux.