NetBSD is excellent if you need support for strange, obscure platforms. The biggest problem with NetBSD is that if you work on it (for example, hacking its kernel), you end up working for companies like Apple gratis, because the BSD licence offers no protection against proprietary use.

NetBSD is still excellent however, even if it is saddled with a poor licence. I recommend it as a good SunOS alternative for older Suns, and as far as old VAXen go, it's either NetBSD or 4.3BSD.