Probably the best jet "trainer" relating to learning fast jet flight dynamics and orientation would be the Kangaroo/Rookie/Hotspot designs. If you can take off and land the Roo/Rookie/Hotspot on the money consistently your probably ready for the faster and heavier scale jets in general.
On the otherhand if your looking for "EASY" to fly those previously models mentioned up above are some good options.... although probably more so "flight trainers" than ideal "fast jet trainers". The Bobcat and Velox are worth looking at also with wide flight performance envelope and easy turbine access that would be good jet intro/sport flyers....