Well one major thing is that tramp is inside emacs so you can configure it with elisp, which is a major plus in my mind. The main problem with tramp is that Emacs is single threaded (and elisp threads run one at a time), so networking operations can be iffy. On most normal connections it works fine in my experience. Another reason to use sshfs is if you're switching between Emacs and a separate terminal, you don't need another connection. That goes away with vterm since now you don't need a separate terminal (it fixes a lot of the traditional problems with ansi-term, shell-mode, and eshell. Although there's a good argument to make for using eshell as your main shell).