Nostr is a far more robust protocol than Farcaster. 

Here are a few simple metrics:
Github contributers: Farcaster: 20, Nostr: 132
Open Pull requests: Farcaster: 3, Nostr: 199
Social clients: Farcaster: 2 (but really Warpcast has 90%+ of users), Nostr: Too many to count 😂 (https://www.nostrapps.com/)

From a technical standpoint, Farcaster requires a global consensus amounst all hubs (the servers that store the data). This means that in the case of a hostile regeime pressuing a hub operator to remove certain posts, they would be force to complelty fork off of the network. (Global consensus also means that at scale, hub operation will get very expensive and out of reach for all but the largest clients). Nostr on the other hand operates through relays that store and serve posts and events. You can have a small relay that only stores the events from you and your followers, or a larger relay that anyone can write to. There is no "global state" so the network can never be out of consensus, you just query the relays that your friends post to to retreive their events.

And lastly, requiring users to pay a centralized entity to sign up (the cost of which is subject to change on the whim of the founder) is not a free and open protocol.