I don't have a "modern" vehicle but automated following distance is the only thing I feel like I'm missing out on. Everything else feels like I'm dodging bullets.
Unfortunately not upgrading means missing out on improvements to physical safety in the event of a crash.
Auto headlights switching is nice as well. We have it on the Lexus.
You might be able to add that feature yourself. Comma/open pilot looks really cool
https://comma.ai