The second path, although more expensive, is a shorter trip to the CCNA. Instead of studying for and taking two separate exams, you can opt to take the single CCNA (200-125) exam. Technically, there are no prerequisites to earning the CCNA no matter which path you choose to take. However, you will not be certified as either CCENT or CCNA if you take ICND2 before you take ICND1.
There are some obvious pros and cons for each of the paths. For example, taking the single CCNA exam costs more up front and requires a broader range of study than taking the two ICND exams individually. However, you’ll only need to sit a single exam. Taking the two ICND exams individually will allow you to split the total cost of certification over time, but you’ll also be required to study for and sit two separate exams.
A perhaps less obvious pro of taking the two-exam path is that you obtain a certificate sooner than if you study with the exclusive goal of obtaining the CCNA. If your certification goal includes being able to demonstrate to employers that you are on your way to the CCNA, taking the two-exam path might be more worthwhile than taking the single exam. It will also be less expensive to retake ICND2 should you already have the CCENT and fail to obtain the CCNA than it would be to have no certification and have to retake the single CCNA exam.
In the end, the path you choose comes down to your personal goals, preferences, budget, and security in your knowledge of the material. If your goal is to obtain a certification and demonstrate that you are motivated to go further, take the two-exam path. If you are already certain of your skill set or you simply need to recertify, taking the single exam path might be a better choice.
Your author has no access to statistics that might indicate which path the majority of CCNA candidates choose so, in this case, I can’t tell you which path would fit Robert Frost’s definition of the road less traveled. Instead, choosing the path that best fits your own goals is the one that will make all the difference.