Best Dervish form for PvE?
The one Casey Squid
Just got to the point where I can cap em and I was wondering whats the best one for general PvE usuage...
Knightsaber Sith
Well I found Balthazar to be very usefull for tanking in gates of madness.
Ulivious The Reaper
i beleive in nightfall it's between melandru and balthazaar, i'd lean towards balthazaar because i'm a total warrior freak and if i can make my dervish as cool as my warrior then i sure as hell will!! 
as for melandru, with all the conditions i see getting spammed around i tend to bring I Will Survive (i think thats the skill) on my warrior, as a dervish with melandrus avatar you won't need condition removal, so yeh, your choice
heres another link with information about the forms to compliment knightsabers link http://gw.gamewikis.org/wiki/Avatar
as for melandru, with all the conditions i see getting spammed around i tend to bring I Will Survive (i think thats the skill) on my warrior, as a dervish with melandrus avatar you won't need condition removal, so yeh, your choice
heres another link with information about the forms to compliment knightsabers link http://gw.gamewikis.org/wiki/Avatar
Knightsaber Sith
and guildwiki of course has the locations
http://gw.gamewikis.org/wiki/Elite_s...list#Nightfall
http://gw.gamewikis.org/wiki/Elite_s...list#Nightfall
strcpy
Avatar of Lyssa also looks to be pretty good from its description. +10 energy and +41 damage at mysticism 12 to foes activating skills. In my experience many of the PvE enemy is constantly activating skills. This would be especially potent when you get some support character grouped, with heart of fury (attack 33% faster), and using a +damage scythe skill.
Though I have no experience with it - once you do the cemetery mission the Acolyte of Lyssa no longer spawns in Sunward Reaches. No one has found a second spawn point as far as I know and Anet hasn't put in a fix. I didn't start capping skills until right after finishing the cemetery.
Personally I prefer Balthazar's form (+40 armor is nice) over Melandru's. Mainly because Melandru's form cost 25 energy so if you have any DP at all you can not use your elite. Though I generally prefer Melandru's stats. If you are activating lots of skills or are in a hex heavy area Avatar of Dwayna looks nice also. I don't see a large use for Grenth in PvE, but I haven't made it to the desolation areas (I think they are called - after I complete my current mission I go there).
Though I have no experience with it - once you do the cemetery mission the Acolyte of Lyssa no longer spawns in Sunward Reaches. No one has found a second spawn point as far as I know and Anet hasn't put in a fix. I didn't start capping skills until right after finishing the cemetery.
Personally I prefer Balthazar's form (+40 armor is nice) over Melandru's. Mainly because Melandru's form cost 25 energy so if you have any DP at all you can not use your elite. Though I generally prefer Melandru's stats. If you are activating lots of skills or are in a hex heavy area Avatar of Dwayna looks nice also. I don't see a large use for Grenth in PvE, but I haven't made it to the desolation areas (I think they are called - after I complete my current mission I go there).