I would actually say it is far more important to have a good mentor then to have a track, at least if you are planning to pursue any sort of academic career. Perhaps others can speak more towards the clinical side of things, but I imagine it would be immensely helpful there as well. You can really focus in on a specialization, they will probably be familiar with (or themselves have appointments at) many practica sites you will be interested in, etc. Even if you are clinically-focused, don't underestimate the amount you can learn about clinical work in a good research lab. We're primarily addiction neuroscientists in my lab, but it has still helped me clinically. I imagine a lab that does more "clinical" research would be even more beneficial.
Be careful of programs with "tracks". Some are legitimate and offered by some great programs (e.g. U Miami). Overall though, it seems like they are more commonly used as an "advertising scheme" to draw people into schools with questionable reputations. A track itself won't open any doors for you that getting the same (or more commonly, better) experiences at a school that doesn't have a formal track will.
