I really hope they get the classes right, as well as the leveling curve, in EQN.
There was nothing rewarding about leveling in GW2. You were doing the same things at level 50 that you were doing at level 10. You were using the exact same skills and abilities. Your gear was doled out to you in a predictable manner with ever so small +gooder upgrades, which where pretty much negated by an under the cover level-scaling-to-gear system anyways. All of the classes could play the exact same way (melee, ranged, support), if you simply changed your weapon out.
In reality, EQ was much more of a grind than GW2, but it didn't feel that way. EQ staggered it's class defining abilities across the entire level range, so that you were playing a much different character every 4 to 8 levels. For instance, the EQ1 Shaman... at level 10 you were a SoW bot. At level 29 you were a solo machine with Regeneration and Cannibalization. At level 44 you were given over powered Dots and were a DPS machine. At 50 you were at the height of your powers and completely balanced class that could do it all... solo, group, crowd control, buff boss, heal, and dps. Now that is a rewarding leveling curve.
Combine that with the fact that they allowed gear to drastically modify the balance of your character, and you always felt like you could "cheat the system" and get a leg up. If you were one of the lucky few to have a Rubicite Breastplate, it was going to drastically cut down on your downtime, which made you more efficient, and thus made you more powerful. But, for all of those things to fall into place, you had to have down-time to begin with.
EQ was great because it put all these really shitty challenges in front of you, and if you were resourceful enough, smart enough, and played enough, you could blow right past most of them. No game since has ever attempted to have the depth that EQ1 did. Every game these days removes complexity for the sake of balance, which has created a bland and unrewarding MMO experience.