I used to be one of the "old guys" fighting against git because subversion is "good enough" and I didn't want to relearn a new tool. I finally had to learn git because a project I contributed to made the migration and I could no longer postpone it. I'd never, ever, go back.
At this point I'd go as far as saying that git is objectively superior to SVN because it does everything SVN can and then more. One caveat being potentially very large repositories and especially repositories containing sub-repositories, git was terrible at that and while it's improved over the past decade it's still a bit messy. Unfortunately in my experience these types of repositories are fairly common in proprietary codebase where people often don't hesitate to commit big binary files alongside the source code.
Still, I'd say that as a rule of thumb if a codebase is still in active use it's probably worth taking a week or so to migrate it to Git unless there's a very good reason not to.
SVN has its limitations, but having used Perforce in my last job and now using Git, I wouldn't mind going back. It's a judgment call, as the two systems have different strengths and weaknesses, but I don't find Git to be an overwhelming improvement. For instance, in Git, if you merge from branch A to branch B while work is underway on both, then merge A to master — and assuming you're using squash merges, as is pretty much essential to get a readable commit history — and then merge from master to B, you're in merge hell, because Git doesn't remember that the squash-merge commit contains some of the changes that were already merged to B. Perforce gets this right: it gives you an equally clear master history, with a single merge commit each time you merge from a branch, but doesn't lose the relationship of that to the individual commits in the branch.
At this point I'd go as far as saying that git is objectively superior to SVN because it does everything SVN can and then more. One caveat being potentially very large repositories and especially repositories containing sub-repositories, git was terrible at that and while it's improved over the past decade it's still a bit messy. Unfortunately in my experience these types of repositories are fairly common in proprietary codebase where people often don't hesitate to commit big binary files alongside the source code.
Still, I'd say that as a rule of thumb if a codebase is still in active use it's probably worth taking a week or so to migrate it to Git unless there's a very good reason not to.