It's odd with this EDC thing as some folks see it as kind of a badge of honour.
For me everything depends on what i'm doing.
99% of the time i carry a bum bag, i'll have:
Mobile phone in a pouch on the side -
obvious reasons, plus i'm usually on-call for work
Wallet
obvious reasons
Keys
obvious reasons
Drivers license and ID
obvious reasons
Torch (usually a Zebralight SC600)
Gets a LOT of use, from power cuts while on the toilet, through to helping folks who have broke down, i charge the battery once a week and that's usually 2 hours use a week all in
Leatherman skeletool CX
Don't use this much but when i do it's usually needed
Doug Ritter RSK large lock knife
Use this even less and it often stays at home
USB drive (work transferring files etc)
Used a couple of times a month
Small collapsible pen
Very very rarely used
Whistle
I live in a very active earthquake zone so i usually have a whistle in every room of the house and clip small whistles on or in everyones bags
Basic FAK the contents of which i'm happy i know how to use:
Couple of plasters
with the kids these usually get rotated a LOT (both 11)
Resuscitation mask
hopefully i'll never need to use it, but if i do i 100% want it there ready
2 x Nurofen
Usually popular with the women 
2 x soluble
a few relatives with heart problems
Eye drops/cleaner
I get hayfever and again 2 very active kids
2 x Imodium
Greek food 
1 x Blister plaster
usually get through a couple a year
Antiseptic wipe
obvious reasons
Tweezers
obvious reasons
Sounds a lot to carry around daily, but the FAK fits in a very small aloksak and everything fits in the bumbag easily and i don't really notice it any more.
If i'm out hiking i usually take another bag with a more comprehensive FAK with things like small splints, tick remover, bandages etc.
In winter i'll take an emergency bivvy shelter and in summer i'll load up with as much water as i can comfortably carry.
In the cars i have FAK's aimed towards RTA's, again usually between 3 and 6 litres of water and sunblock, in winter i'll throw in some wool blankets and emergency bivvy bags and thick reflective coats.
If i don't use something then i tend to not bother carrying it
Things like water and sunblock is just sensible in a country that sees mid 40c's ambient temps, likewise the whistles.
I'd sit down and think about what you'd have liked to have near to hand over the last year.
Word of warning though you can't even begin to carry everything you could possibly need, and if you carry a FAK make sure your trained and comfortable using everything in it.