Panama City is an amazing deal. Went from the Hotel Continental (I think ) to the Miraflores locks on the canal. Easily a 50 minute drive in traffic for $5. It was amazing. Taxi was barely fit for the road, but hey, you get what you pay for....

Singapore and Hong Kong are awesome values as well. Factoring the exchange rates, I was suprised how cheap they were and worked really well in a pinch.

Shanghai ones were also really great. Little crammed but I'd go from my friend's apartment near Xiujuahai to pretty much anywhere in the city for $5... not the great deal that PTY was, but it was pretty sweet.

New York is very reasonable IMO. I don't think it's too expensive and when in a pinch, works great.

Tokyo ones are really nice but a taxi ride that really amounted to like 4-5km from Roppongi to Shibuya cost a whopping 2500Y... yikes. The drivers wear suits, the doors automatically open and they also wear white gloves... it's a nice service if you got the cash for it.

Worst could be Tijuana Mexico. Dangerous driving, unfit for the roads and really pricey if you're not well versed on what a trip could cost. Conviently.. lot of taxi drivers love to forget the previously negotated rate and won't take f'n PESOS in MEXICO.