That said, I encourage players to to play to their PC's strengths. At least initially, the choice of PC will dictate what you're good at and where you can excel.
Examples:
Lelouch will be best used gathering information and developing tools/technology/strategies to see victory. He'll be a good character for small delicate (black) operations or building a tech empire.
...again, though, you've got time. There isn't a ticking clock in this quest. Unless something goes drastically wrong, Charles has another 20 years on him before health concerns start settling in. On the other hand, while becoming Emperor/Empress is the ideal outcome for eventual plans, it's not absolutely necessary depending on how the quest goes. Lots of possibilities to advance your interests as the PC.