Need cash when I land, best place in Timor-Leste? Airport or places in the city?
My advice is to skip the exchange counter altogether. Most cards work at the ATMs, and you'll get a much better exchange rate than you will from any exchange booth. The ATMs are plentiful in Dili, so you can find a bank easily. I used my Visa card at a Bank Mandiri ATM, and the rate was perfect. Just withdraw what you need for the day and then use your card for larger purchases.
The airport is the worst place to exchange money in Timor-Leste because there are no currency exchange facilities there. You must have cash with you to pay for your visa on arrival and to get a taxi to your hotel. The best and only option is to use an ATM in the city. The ATMs from banks like Banco Central de Timor-Leste or the BNU (Banco Nacional Ultramarino) in Dili are reliable and will give you a good rate.
I've been to Timor-Leste many times, and the best way to get cash is to use an ATM in the city. The airport's currency exchange booths are not an option; they don't exist. The currency is the US dollar, so you'll be able to use your debit card at any bank ATM. I've used the one at the Bank Mandiri branch without any issues. Just withdraw what you need for the day and then use your card for larger purchases.
Don't even bother with the airport exchange counter. It's a waste of time. The official currency is the US dollar, so if you have it, you're all set. If you're coming from another country, your best bet is to use an ATM in the city of Dili. The ATMs from banks like Bank Mandiri or Banco Central de Timor-Leste are generally reliable. You'll get a much better exchange rate there than you would from any currency exchange counter.