I think you should focus on the last trainee, he's got pretty good starting skills and now you know how to train properly, you can make a great salary efficient player of him. The first one probably won't reach his cap anyway, but if you can keep training him in the plan you have for the last guy so he'll still get better. The 2nd guy is nicely balanced though not that many skill points, but he can be useful if you keep training him. You could however get a similar trainee for practically free of the TL with same potential/skills (maybe a bit fewer skill points) but then 18 years old.