When does a class sort of.. starts to open up?

I have a lvl 60 hunter who I’m raiding with, have the epic mount etc etc. So there is not much left for me to do, so I am starting to think about leveling an alt.However, I really can’t decide which one I like best so I was thinking of leveling them all for a few levels to see which one stands out. So I want to do this for Druid, paladin, mage, warlock and warrior.So I was first thinking about leveling them to 10. But then you only get your first talent point and I feel like not a lot changes... so.. I was know thinking about leveling them to lvl 15.So my question is, would that be a sweet spot to really see a class opening up and having the basis mechanics? Or should 10 be enough?? Or can’t you really say that much until like lvl 20 and up?