Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Agree with the candidates for most powerful, but I think Pants-positive safety's use very much depends on what guns are being used and their condition of readiness.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Influence quirks are some of my favourites. Get what you want from people without any of the risks associatd with attempting to influence them, or at least open the door.

Magical Weapon Bond is one I consider almost standard among warriors in fantasy settings.

I see Quirks as a contract between the player & GM; an agreement that said characteristic will occasionally become relevant to the inconvenience of the player, using the "wears black" option it would be opponents get +1 to find you because they know what colour to look for (and perhaps -1 to find the person who hasn't got the quirk but wore black the past few times they met but is wearing something different today) and -1 to reaction rolls on occasion (Angel: "Do I look intimidating?" Cordelia: "Maybe you might want to think about mixing up the black on black look".)

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

I'd argue that your most powerful perks are usually going to be rule exemption perks, things like Infinite Ammo, or "I get to use TV Action Violence" or "I can ignore friendly fire" etc. They have potentially the farthest reach, and need the most attention from the GM.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Most trivial quirk was for an ambidextrous character who went with this double
1. Left hand dominant
2. prefers using right hand

so although they used either hand equally well they naturally defaulted to their left hand but they forced themselves to use their right hand.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Or Extra Option. I found Speedy Enchantment a much appreciated option.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

There are places in Gernsback-2 where she'd be out of uniform if she isn't wearing high heels. "High-Heeled Heroine" is a very useful Perk.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Rules Exemption, Extra Option, etc are probably going to be the most powerful metaPerks (that is, Perks that change the way the game works for your character). Aside from that, the various "Negates a penalty my character would take all the time otherwise" Perks (Shield Wall Training if you use a Large Shield - or any shield with the optional rule from LTC2, Exotic Weapon Training if your primary weapon suffers such a penalty, Off-Hand Training if you dual wield, etc) are highly useful. For least powerful, the various non-combat Shticks aren't so great, Cross-Trained is rarely relevant (and high skill gets you a large number of Familiarities anyway), and One Task Wonder is useful for defining a character, but not so great in terms of what you get (it's basically like putting [1] in the skill, then narrowing it down significantly to turn it into an Easy skill, but not being able to invest further).

As for Quirks, Power Ups 6 gives some really good guidelines for defining and using them that should be good enough for figuring out if a Trait should count as such.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Dislikes Carrots is an EXPLICITLY allowed quirk, check B164 under dislikes.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Deep Sleeper (especially in combination with Combat Reflexes) is perennially underrated but incredibly valuable when it comes up.

Re: Most trivial quirk, most useful perk, least useful perk, and most severe quirk.
 

Yeah, it's all the benefits of the Light Sleeper disadvantage with none of the drawbacks, presuming Combat Reflexes on the character (which someone with either trait should have).