Assuming you are carrying a spare tire as well, I favor the following. With these basic tools, you and a good Samaritan can change your tire on any solid flat surface.
- 6 ton bottle jack (it does the job well, is smaller and much lighter than a 12 ton)
- a 1/2" breaker bar and a pipe to slip over it for better leverage
- appropriate size 1/2 deep well socket that fits your lugs
- square piece of a 2x8 board to support the jack better in gravel or dirt
If you are like I was many years ago and wondered what exactly is a breaker bar, it looks like this, a 1/2" socket connector like a ratchet wrench has. All I seen have a nice pivot head feature. You can buy them on ebay and on-line stores for around $25 for one 24" long. The longer the better.
If your flat is a clean puncture like from a nail for example, then there are road-side flat-fixing kits available at Walmart for around $60, allowing you to repair the tire while still on the vehicle. I carry such a kit in my tow vehicle. It has a 12v compressor, rope patch, tools, all you need to repair and fill the tire while on the vehicle.
Here is the kit I carry. The bag is quite small.