Confused new player on order to play campaigns.

I am coming from GW2, but before that I played Anarchy Online for ten years so I am not adverse to a more difficult or in depth game. I am not playing Gw for the GW2 achievements, and I am not ina rush to complete the GW content. I would rather play to get the best experience from the game, so I don't want to spoil the story by jumping around too much and getting ahead in the story.

I feel like I can figure out most of the mechanics of the game from the Wiki. My problem is more related to which campaign to play first. I would rather play them in order of release, but I am worried that not having heroes from other campaigns will make it too hard?

I have been doing some reading and some people say that for new players henchman are better than heroes if you don't have the skills unlocked. Some people say heroes are a big improvement and I will need them to get through prophecies?

Right now I have a necro in nightfall at level 7, and a ranger in Ascalon level 7. As far as I can tell my options are to do the story to unlock heroes on necr in nightfall and maybe some of EOTN and then head to Prophecies to do the story. I don't really want to do this if it spoils too much of the story. Otherwise I can do the campaigns in order on ranger if it is possible without heroes.