I really love Guarucoop airport taxi. Arriving at São Paulo's GRU airport, just head past the baggage claim and outside to the branded kiosk. You pay a flat rate to get to the city (it's R$140 for me to get to Pinheiros), offer the attendant your exact address and then have the ability to pay the full amount on your credit card.
If you're lucky, there won't be a line and you can just hop in a taxi, but if it's a Monday around 8/9am, you may have to join the line. The worst I've had was 45 minutes (and that's after landing from an international red eye flight).
The pros: you can pay with your card in advance, no language barrier issues, no worrying about whether the driver will take the long route to run the fare, nice and clean cars. read more