A jet trainer. Start with the J-7 and if you do well move up to better birds.
I wonder of type 59 tanks are used for the same purpose. Must feel similar getting assigned to one.
One downside with this approach is that 2nd gen fighters handle differently than 4th gen birds. Even if you fly a J-7E with modern avionics you still have different thrust and aerodynamics. This is why they need more L-15s.
Why is this in J10 thread? If we are going to be off topic, I'll pitch in. J7s are still used as advanced training for a lot of the pilots very much like @no_name said. The thought process is that a J-7 much harder to fly than a J10, or flanker, and that it is good to train the basics of combat flight training. It is also very very cheap to fly compared to other 4+ jets. Think of it like the Navy using a sail boat to teach seamanship.
I think there was a news around mid this year suggested the newest batch of airforce junior pilot was trained in CJ-6, JL-10 then directly J-10, so yeah, don't know how long those J-7 could still be used even as training