Maintenance for the week of October 5:
• [IN PROGRESS] ESO Store and Account System for maintenance – October 8, 8:00AM EDT (12:00 UTC) – 12:00PM EDT (16:00 UTC)
And as for the question all can increase your damage, warrior and tower give the most gains for sustained damage while the thief and shadow are useful if you already have high power or stam it all depends on your build.