You are the best person to nominate the names. If you seek advice from learned & experience members than first share what kind of training and trainers being conducted at your office.
You can choose the best name on basis of following points:-
1 Feedback of the training.
2 Utility and commercial value.
3 Cost analysis, effectiveness and individual's growth.
4 Expertise of the trainer, way of training and trainee involvement.
There may be many more points. You can set up a "Judiciary Bench" to decide the best trainer.
Hope the above will help to resolve your query.