I trained a ton of people back in the 80's and my favorite trainer was the Avistar. There is a good reason that airplane has been around for so many years. It's capabilities are incredible. You can use it for primary and advanced training and even beyond. Don't be fooled by its appearance. That is a very capable machine.

If you are focusing on advanced training, then i recommend the Stiks. They are great for learning to land airplanes with symmetrical airfoils and medium wing loadings. Also, the Super Sportster makes a great advanced trainer. It is capable of very high speeds, and still lands very slowly. IT is an excellent airplane. It might be slighty too advanced for some people. I tend to call it a great third airplane.