Selfhosted

I use Headscale, but Tailscale is a great service and what I generally recommend to strangers who want to approximate my setup. The tradeoffs are pretty straightforward:

• Tailscale is going to have better uptime than any single-machine Headscale setup, though not better uptime than the single-machine services I use it to access... so not a big deal to me either way.
• Tailscale doesn't require you to wrestle with certs or the networking setup required to do NAT traversal. And they do it well, you don't have to wonder whether you've screwed something up that's degrading NAT traversal only in certain conditions. It just works. That said, I've been through the wringer already on these topics so Headscale is not painful for me.
• Headscale is self-hosted, for better and worse.
• In the default config (and in any reasonable user-friendly, non professional config), Tailscale can inject a node into your network. They don't and won't. They can't sniff your traffic without adding a node to your tailnet. But they do have the technical capability to join a node to your tailnet without your consent... their policy to not do that protects you... but their technology doesn't. This isn't some surveillance power grab though, it's a risk that's essential to the service they provide... which is determining what nodes can join your tailnet. IMO, the tailscale security architecture is strong. I'd have no qualms about trusting them with my network.
• Beyond 3 ~~devices~~ users, Tailscale costs money... about $6 US in that geography. It's a pretty reasonable cost for the service, and proportional in the grand scheme of what most self-hosters spend on their setups annually. IMO, it's good value and I wouldn't feel bad paying it.

Tailscale is great, and there's no compelling reason that should prevent most self-hosters that want it from using it. I use Headscale because I can and I'm comfortable doing so... But they're both awesome options.