Grieving vs Viper

Is there a comparison between Grieving and Viper? More specifically what are the best condition builds on any profession to use Grieving over Viper (if any)

While Grieving and Viper are fairly similar, the only stat difference is that Grieving uses ferocity and Viper uses expertise or longer condition duration. Most condition builds in fractals and raids such as core engineer need the expertise because most of the engineer's kit skills have low cooldowns and can apply conditions very frequently.

I believe that the only time Grieving works is in WvW on professions like scourge. Most zerg groups in WvW have firebrands who can cleanse those conditions easily so the longer condition duration doesn't matter that much.

Grieving is good if significant portion of your dps is power and/or if you have 100% condition duration from other sources. This can happen if your class aply only one type of condition but in huge numbers so you can get much higher duration from sigils/runes.If your class doesnt have this then viper will provide better dps.

Expertise is like condition version of precision. Once you get to 100 percent crit/duration rest will be wasted but until you are at 100 percent they increse your dps by alot

Nike made a video about it a long time ago

Grieving if your class mainly applies one condition and can boost it to 100% with runes, sigils, food, traits.Viper if your class applies many conditions and needs to extend them all.

If you're looking for better survival, Viper is by far better than Grieving, because you not only do more damage over time, but all the soft CC you inflict becomes debilitating, we're talking like 20+sec Cripples from some skills and whatnot.

However, beware that in PvP and WvW, Condition Duration doesn't matter much (unlike PvE) due to cleanses.

Actually viper + grieving mix is reapers top condition build for raids I believe