Both the Yamaha R15S and the FZ25 are great bikes, but the choice between them depends on your preferences and riding style. However, considering your height of 5.6 ft (around 170 cm), I would recommend the Yamaha R15S for the following reasons:
Lower Seat Height: The Yamaha R15S has a relatively lower seat height compared to the FZ25, which makes it more suitable for riders with shorter inseams. This allows for better stability and easier maneuverability, especially at low speeds or when stopping.
Sporty Riding Position: The R15S features a sportier riding position, with slightly forward-leaning ergonomics. This can be advantageous for riders who prefer a more aggressive and engaged riding stance, as it offers better control and aerodynamics.
Lighter Weight: The R15S is generally lighter than the FZ25, which can make it easier to handle, especially for riders with a smaller stature. The lighter weight contributes to better maneuverability, making it ideal for city riding and nimble cornering.
Performance-oriented: The R15S is designed as a sporty and performance-oriented bike. It comes with a peppy and responsive engine, advanced features like a fully digital instrument cluster, and aerodynamic fairing that enhances its sporty appeal.
Ultimately, it's important to test ride both bikes and see which one feels more comfortable and suits your riding style the best.