which car is the best for me and good gas milage?

Civic. Everything is cheaper about the civic. Reliable too. Easy access to parts. Just get a quick release steering wheel or an alarm system as they’re always stolen. And with the right parts or even just nice wheels, you can make it nice. Just don’t rice it (please don’t), or you’ll prove others right about the civic stereotype. 

None of the above

Nissan Leaf EV .  does not need gas.

Civic but get a type R.

The Honda Accord would be a great choice. However stay away from a 2003 or 2004. They had transmission issues. 

2018 Ford Focus 1.0L 6spd manual - I am getting 43-46mpg highway consistently. 

Well you listed compact and midsize sedans. The civic and elantra are smaller cars that will get better gas mileage but have less room in the back. The Sonata and Accord are midsize sedans that will get a little worse gas mileage but will have more room in the back. So it's your choice if you have kids then a midsize sedan would be better but if you don't have any kids then a compact sedan should be plenty enough.

It doesn't really matter because finding a car at a low price is going to make far more of a difference than getting good mpg. Look for a toyota corolla or something. Or a honda civic. If you can get an elantra with a manual transmission then get that. They're all decent cars but the real trick is finding one for sale in good condition at a low price. Don't worry about gas money that much. It's really the break-downs and repairs that are going to cost a lot unless you do all your own repairs and maintenance yourself.

Real Life  mileage, from Fuelly.com:

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1. 88-07 Honda Accord  --  about 24 mpg

2. 94-05 Honda Civic  --  about 30 mpg

3. 09-15 Hyundai Elantra -- about 30 mpg

4. 08-16  Hyundai Sonata -- about 26 mpg

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My choice for my daughter was the Mitsubishi Mirage -- about 38 mpg.

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ANY car over 15 years old is about to have problems from plastic breaking.

For better fuel mileage you want a vehicle with an CVT.

Nobody here knows what the best car for you would be. Throwing out random used cars is meaningless because not every 92 Accord (for example) is worth buying.