Here's a rough layout of what i'd like the vanguard class to be like. All trees should be viable in both PvE and PvP:
Shield Specialist
PvE: tank
PvP: protecting (squishy) allies
Haven't played this spec much after 2.0, but i think its doing allright. Could do with a bit more defensive cd's tho.
Tactics:
PvE: sustained dps + cc support
PvP: tactical dps
This tree needs some work. While it lacks both survivability and burst in PvP, it should have some tricks up its sleeve like more cc's, like another stun (mezz?) or actually good slows for kiting . Also there's not much tactical about having to go into the fray, so give it some ranged abilities. This, along with the sustained dps should make it viable in PvE too.
Assault
PvE: (burst) dmg
PvP: burst dmg
Needs it's burst back, simple
my 2c's