@Roggles, one dodge forward + Infiltrator's Arrow + Stealth is more than enough to get away from anyone
Especially if you're using your Infiltrator's Arrow over roofs.
All in all, here are all the ways a Thief can get Stealth :
Steal with Hidden Thief (30s CD)
Off-Hand Dagger : Cloak and Dagger (5 Initiative, No CD)
Shadow Refuge : Mass Healing + Stealth while inside the refuge (60s CD)
Shadow Trap : Vanish + Shadowstep to the trap on trigger (30s CD)
Blinding Powder : Mass Blind + Mass Vanish (60s CD)
Hide in Shadows : Vanish + Regen (30s CD)
Now let's see. Steal and CnD are almost mandatory in a PvP setting mostly because of the Stealth factor itself. The off-hand Dagger insures that you're always able to Stealth whenever you have 5 Initiative (Do you need a target ? Not sure). Shadow Refuge is a PvE ability, or at best something you'd use in WvW. The only cool use in a 1v1 situation I can see is pre-stealthing, popping Shadow Refuge somewhere and go chill there. The pre-stealth is to avoid your opponent seeing you enter the Shadow Refuge and just AoEing the hell out of you. Could be interesting to do, but yeah it's a 60s CD and you can probably find better 60s utilities. Which leaves us 3 good looking Stealth abilities on top of CnD and Steal. I'm just gonna dismiss Shadow Trap. It is certainly great, but it focuses on offense a little too much and most importantly it requires your opponent to trigger it, so it's not really on demand, more like : when i'll be able to fool him into the trap. Great for ambushes and openers, but I'm not sure it's that great in the heart of the action. Which leaves Blinding Powder and Hide in Shadows. Honestly, both are very great tools and depend entirely on the play style and the situation. Anything with Blind is good in my books, must be a great feeling timing it just before your opponent goes for his heal and see him miserably miss. Hide in Shadows has that sexy 30s CD though, so ... yeah ... on the fence here. Should also depend on how much you'll actually need that 3rd vanish in battle.