Necro or Thief
Define usefulness. Necromancer isn’t the optimal choice for most pve content, but it certainly doesn’t carry the stigma that thief does in that part of the game. In pvp we have a few builds that are very deadly. In all honesty this is about gameplay preferences and aesthetics, level both to 10 and decide what you enjoy the most.
Vile Necromancer||Defender of the Beastgate||Slayer of Moa’s
As surely a lot of people had already told you, roll both and try them. Both of them have very different playsstyles, so try them and choose which one suites you better.
imho, both are very good choices. Probably necro will be best to PvE (fractals, dungeons, open world) and thief will be a better option on WvW.
Morbridae (Norn Necromancer)
@ Sorrow’s Furnace (VE)
@ Sorrow’s Furnace (VE)