That is an extremely broad question. You have qualified best, by saying strongest learning. My honest answer is The Mirrer Yeshiva in Yerushalayim. You can get whatever type of learning and shiurim you want there. But on the flip side, it is also the easiest place for a bochur to ‘get lost’.
Is the boy a shtark learner who knows very well what his goals in life are? Or does he tend to get distracted?