The one big thing that you should realize early on about this game is that there is almost no difference in your overall level of character power at level 1 vs. level 50.

You do unlock active abilities and passive skills as you level. But more than half --- probably more like 80% --- of the "progression" of your character in this game comes from learning how to assemble all the various pieces available to you into a working build with strong synergy, and then gaining the (player) skill to play that build to its peak potential. And then learning how to adapt to different situations with other builds that you also can play well.

Once you are at level 50 with your first character, then you unlock the Champion Points system. That gives you perk points (up to a total of 660) that you can use to unlock more passive bonuses, and, up to CP300, that also passively boost all your stats by up to 20%. Those can be a significant boost to your overall power, and the CP you earn on any character are available to all characters on your account, starting from level 1.

However, there are PvP campaigns available that disable CP entirely, so you still have zones where you can PvP and be on an equal footing in terms of raw stat power available with everyone else. And despite the significant power that the CP buffs give, they're not overwhelming.

The CP system also is biased so that most of the power gain comes from a relatively low level of CP points invested, and characters with very high CP gain far less from the last 300 points invested than you do from the first 300. And player skill; knowing what to play and how to play it well, is always >>> gear or stats any day.

When it comes to gear, the other big difference vs. WoW is there are no gear resets. New content will bring new options, in terms of sets that do different things and enable new types of builds and synergies. But overall, CP160 epic or legendary gear is as good as it gets. You may want to get new and different sets to use with different builds, but you won't need to re-grind gear in six months because everything you have just became obsolete.