Obviously you are getting a lot of opinions and they're all good you just have to figure out what will work best for you.
Me personally, because I ride into remote areas, some of which have no cell phone service, I carry whatever I think I need that gives me the best chance to repair common stuff and get home without bugging my wife.
So what I carry in both unless otherwise noted (one medium and one large for the touring bike) Topeak Aero Wedge bags (one road and one for touring) is:
Spare folding tire folded very tightly (only in the touring bag).
Spare tube (one I've patched up with glueless patches several times, in it's box to prevent punctures).
Glueless patches (which if done correctly will last the life of the tube, plus no surprise dry glue tube, but to be safe I replace mine at the beginning of each season to make sure the self stick glue is fresh; I also only use Park glueless patches because I know those work and some don't; these go into the Altoids tin).
Glueless tire boot (these do not self stick real long, so if I want a permanent repair I put 1 or 2 drops of Gorilla glue close to the middle of the patch so the glue doesn't spread out and attach the tube to the tire; I also will cut the patch before taking off the backing into thirds and only use a third unless it's a large cut; goes into the Altoid tin).
Small tube of Gorilla glue (great for filling in cuts in tires from the outside as well as the patch explained above).
Soma steel core tire irons (the best irons I've ever used, I have a set in both bags).
QuikStik (great for ripping tires off rims fast).
Var tire lever (only in the touring bike because the steel beaded tires are hard to put on and this tool makes it all so easy to put the last bit on).
Park MTB 3.2 mini tool (this has a lot of tools, some think too many but it works for a lot of problems, plus I've used it to fix other bikes and even a car once).
Cheap pair of small folding pliers.
Presta to Schrader converter (in case I need to use a Schrader pump, or in case the presta grommet wears out you can flip it to Schrader and pump; goes into Altoid tin).
Spare computer battery (button battery goes into Altoid tin), and tail light battery.
Duct tape wrapped around the tube box several times
4 Zip Ties (in the touring seat bag)
2 FiberFix spokes (in the touring seat bag)
4 Butterfly stitches, and couple of bandaids (goes into the Altoid tin).
2 Ibuprofen, 2 Imodium AD, 2 sinus headache, and 2 allergy pills (stuffed into a former glueless patch box and put into the Altoid tin)
ID card, Insurance card, ICE numbers (all go into the Altoid tin).
$50 cash (in the Altoid tin).
House key (in the Altoid tin).
Cell phone (in touring bag)
Meal bar for longer rides.
Small ziplock baggie with mix formula for longer rides.
The small stuff fits into a specially designed Altoids tin sort of like this one but I redesigned mine for my purposes, just use your own imagination to make yours:
http://www.instructables.com/id/Bycicle-Survival-Kit-/ I take the Altoid tin out of one bag an putting into another, and the Topeak Aero Wedge bags have a mesh stretch thing on the inside of the lid which fits the Altoid tin perfectly. Everything that is not labeled touring bag I have duplicates of and are in each bag.
It seems like a lot to go into those Topeak Aero Wedge bags but believe it or not it all fits; keep in mind a lot of this stuff is small and goes into the Altoids tin, I love that Altoid tin idea, I discovered it on the internet some years ago myself, it just organizes everything really well into a small box.