I agree that an excellent choice would be a SIG SE, as it will teach you things much quicker than almost any other plane, and is very forgiving.

However, if you do insist on going for a biplane, remember the biggest difference is that it needs good throttle management.

They aren't too difficult to land, but the technique is entirely different from a trainer.

When you chop the throttle, they, um, STOP in the air! There is so much drag in a biplane that you need to keep a few clicks of throttle way past the time in a landing when you would have gone to idle with the engine on a trainer.

Good luck!

-David C.