Thinking about starting and wanted to know about the classes like which one is the equivalent to nightelf rouge/ which one is most needed for groups/ which one is the most fun

thanks

Best bet would be the Burglar Class (very similar to rogue in WoW)

Most needed would be Mistrel - Healers
Wardens or Guardians - Tanks

I played a Guardian got it to level 60 - found it a lot of fun - Having thrice as much life as other PCs and pretty much can handle 3-5 mobs at once