I don't have any one particular favourite, so I'll post my Greatest Hits:
- The Akasaka Palace-Marunouci Subway Line complex at Tokyo R246. It's a right-kink with a flat-out left up the hill an then a right-hander where you just miss scraping the wall on the outside and then use the throttle to haul yourself through.
- Suzuka; all of it. Even the Casio Triangle.
- Kallenhard-Exmuhle on the 'Ring; likewise Klostertal and Wipperman. There's a kind of rhythm to them that just feels right. Plenty of fun in any car, but my personal favourites are the DTMs.
- The insanely narrow downhill section on Citta di Aria, just before that almighty straight. It's hell if you get it wrong, but you feel kind of cocky if you put every wheel right. It makes or breaks the lap.
- Georges V Paris might seem like an odd place for a favourite corner, but the Rue Newton/Rue Gallen corner - the one through the blind intersection - is also great. It's the one corner on the circuit where you can have a go and not risk messing it up.
- Haiphong Road/Nathan Road on Hong Kong and the turn off the Waterfront. Both are blind, both are sharp, and when you get it right, both are quick.
- Turn 1/Turn 2 at Apricot Hill. I've loved it since its debut in Gran Turismo 2, but my only complaint is that the GT4 iteration makes the cars look comically small.
- The final section on El Captain, because of the way the car reacts at speed.
- Porsche Curves and Maison Blanche at Le Mans, because to take it at full speed means you're on the very limits of adhesion.
- The final corner at Motegi because it looks innocet but is really easy to screw up.