"Contractor"-type first aid kit in truck; the kind intended for construction job-site use. Probably $30-$40 or so, don't recall. Another one in the garage, wife's car, etc.
In my BOB, more basic first aid supplies. Band-aids, pain killers, Krazy Glue, etc.
As important (more important?) than 'what' you carry, imo, is training in what to do in different situations. Not everyone's going to go through EMT training (I haven't), but everyone can take a free red cross class or two. They cost nothing, and are very informative, at least to someone who's never been through one before.
Ok, opportunity here to preach about Krazy Glue. That stuff is the best field-expedient "stitching" material I've found. You know how easily it 'grabs' your skin when you're trying to glue something...? It 'grabs' that well when you WANT it to, as well. Get a cut in the woods? (Or in the garage, or wherever) Clean/disinfect it as best you can, and drop some Krazy Glue right on it. Even if the bleeding hasn't completely stopped, it'll seal the wound, hold the skin in place, stop the bleeding, keep out water & bugs, etc. Then after a few days (when it isn't needed anymore), it just goes away all by itself. I can't praise this stuff enough. One 0.07-ounce tube will take the place of a LOT of bandages and stitches in your kit. I've used it for years and keep one in my truck's center console and my duty bag always. Last time I used it was a few weeks ago; a homicide detective cut himself on a scene (what can you expect; he's a detective, not a real cop...

). Dragged him over to my unit and popped the cap on the Krazy Glue, and helped ease his embarrassment.
Seriously, if you haven't considered it, actual "Krazy Glue" brand works wonders in a quick & dirty first aid situation. The other brands, I haven't had as good a luck with. Only caveat I would give is to always carry an unopened tube. Once you open and use a tube, it's likely to be caked up & un-useable the next time you need it; so put it in the kitchen junk drawer and put a new tube in your vehicle, pack, wherever. Only costs a buck & a half, and is very cheap insurance for what it provides.