There's a option for US customers - arbitration in San Diego, California. See
Bitfinex's terms of service. The American Arbitration Association's commercial rules apply, which means for claims up to $75,000 arbitration will cost $1000 up front and an additional $1000 if you lose.
Click here to start the arbitration process.
This isn't a complex case. You put money into a Bitfinex account, and they're refusing to pay it back. Any claims of theft are their problem, not yours.
Bitfinex tried to control the process by naming their own arbitrator: "The arbitrator shall be Michael J. Lee, an attorney in San Diego, California or a substitute arbitrator agreed to by a majority of the three parties to these Terms of Service." But there is no Michael J. Lee in San Diego on the
California Bar Association's attorney list. So that clause does not apply.
There are AAA rules and federal laws about arbitration. Having insisted on arbitration, Bitfinex can't make it one-sided. An arbitrator can't be associated with one party; there are procedures for challenging an arbitrator. ("Unless the parties specifically agree in writing that the party-appointed arbitrators are to be non-neutral, arbitrators appointed by the parties in this manner must meet the impartiality and independence standards set forth within the rules ")
If you win an arbitration award in the US, it can be enforced in Hong Kong.
Between 2011 and 2014, the Hong Kong courts never failed to enforce an arbitration judgement.For claims under $75,000, the median time from filing to award is currently 175 days.
In practice, if you file for an arbitration, you're likely to get an offer of settlement, because Bitfinex is going to lose.