Skill speed is nice for DRK (for a lot of reasons, powerful DoTs, faster MP regen with Syphon/Blood Weapon, etc...) but it murders your TP so much that it's IMO not worth stacking like that. I believe crit is the way to go. Tho I don't avoid skill speed at all. If I get it on my gear, I'm totally okay with it as long as I don't get parry with it. It also feels very good when your GCD is faster. But the TP issue is real man... That's the only problem left with this stat as it is right now. So, avoid parry anyway, but if you can choose between multiple DPS secondaries, I'd say go crit.