I'm probably a bit of an outlier in that I wrote my own.

* https://jdebp.uk/Softwares/nosh/guide/commands/nvt-client.xm...

It works well enough on several of the Telnet BBSes listed here, although BBSes are not what I wanted the tool for, and the operating systems I use it on actually retain either their original telnet client in base or a packaged one.

That's because I tested it against a handful of the Telnet BBSes listed here when I wrote it. (-: