Best Event Girls in terms of raw stats are Lavender and Edelweiss.
Dipladenia is also not a bad choice because she has an unique Ability.
You won't find an Event Girl that is equally good compared to a Gacha Girl though. Not on Nutaku or DMM.
Generally Event Girls are tuned down Gacha Girls but with the access to easy Skill and Equipment Slots.
Don't know about any other good Event Girls. Maybe the others know a few hidden gems?
DMM FKG ID: 986648592
Name: Wutan
Myrdin ; What? Nutaku won't do free rainbow dreassbloom exchange anymore?
oh c'monnnn...
Here is some strong girls for raw stats.
In term of skill set I don't know you have to specific it.
Also Canna is one of the most weak girl in FKG, you don't want to have her except she's yo waifu.
Mountain Lilly seems to be strong enough, thanks. Maybe i should do her quest, but later - i have too much pierce girls for now to level up. And for Canna - she has not so good stats, but not so bad abilities and not as ugly as for example Fatcia, Sandersonia or Calla and is blunt (i have only 1 blunt from 17 5* girls now) so i couldn't find better option among permanent event girls (Edelweiss has better stats but terrible abilities).
About changing assistant - i pressed this button, it becomes gray, no confirmation window, message "assistant leader" near her model revealed, but nothing changed - girls at main screen and search still random.
Go to the Mainscreen and click on the icon in the bottom left Corner:
uncheck this option:
Here is a link which explains all options:
http://flowerknight.wikia.com/wiki/Options
DMM FKG ID: 986648592
Name: Wutan
In term of passive you can replace Canna with Himeyuri and Oshiroibana.
You don't need to stick on type when you building your team.
But it's your team, so your choice.
Also you want to do like this in option menu to fix your assitant problem.
Your storage is unlimited.
You can stock everything in there as much as you want.
I looked at Lavender and Edelweiss and they both have terrible abilities set:
Lavender: Heals 3x more HP from Healing Panels.;
Increases Attack for 2 party members, oneself included, by 10%.
Increases Solar Drive's effectiveness by 20%.
Edelweiss: Party members Heal 10% HP when encountering a Nest Panel.
Increases Attack by 5% when encountering a nest panel. (Up to 15%).
Adds 50 to the party's Speed.
So I don't think that they're any good.
Dipladenia - you mean immune to speed altering? it may be usefull sometimes when there are a lot of webs on mission, so i shall think about getting her after I level up all my pierce girls.
Yeah i know they are terrible skillwise.
Me personally i would only use them for Whaleship missions because they boost your Whaleship TP considerably well.
Dipladenia could be usefull for a few maps indeed.
I can't help you much in the Event Girl sector. I don't use them much. I only collect them and lvl the Event Girls which i personally like in terms of looks,voice etc.
DMM FKG ID: 986648592
Name: Wutan