Among the Royal Enfield lineup, the Interceptor 650 and Continental GT 650 models are often regarded as having relatively lower levels of vibrations compared to other models. These bikes feature a modern parallel-twin engine and have been designed with improved balance and reduced vibrations in mind.
It's important to note that individual experiences with vibrations can vary, as personal perception and tolerance for vibrations may differ. I would recommend visiting a Royal Enfield dealership or speaking with current owners of different models to get firsthand feedback about the level of vibrations in specific models, as Royal Enfield continues to make updates and improvements to their motorcycles over time.