3x-ui or Marzban? People argue features, but those barely differ.

Both run on Xray-core, both do VLESS and Reality, both give you a dashboard, traffic stats, and a Telegram bot.

The real question is: how many users are you serving?

One server and a handful of users, run 3x-ui. It's a single Go binary, light on memory, up in minutes, and simple enough that you won't fight it.

Many users, or servers in more than one location, run Marzban. Real database, full API, and one panel that controls multiple nodes, so a user connects through any of them on the same subscription link.

That's the whole decision. Small and simple, 3x-ui. Large and multi-server, Marzban.
Full breakdown, including where 3x-ui starts to strain and why: https://www.doprax.com/blog/3x-ui-or-marzban-pick-by-how-many-servers-you-run