I own both a Leaf and a Plug-In Prius. I drive the Prius on a 20+ mile commute each way, and my wife has been driving the Leaf on her 6 mile each way commute. On the Prius I have been able to get about 100-104 mpg on my way to work on a full charge (20 miles). I get about 57 mpg on the way back home. I'm working on getting a plug at work so that I can average the same coming home as getting to work. The Prius is our long distance car as well. If we have to make trips out of town, that's the car. The Leaf is primarily for my wife's short commute and running around town or nearby neighboring towns (grocery shopping, go to the movies, etc, etc). If the round trip would be more than 60 miles with no place known to plug-in, the Prius is the car we use. Shorter than that we use the Leaf. I have 1 240 volt charger at home and usually use that for the Leaf. I also ran a dedicated 120 volt socket for the Prius in our car port. On weekends I might plug in the Prius on the 240 to get a quick charge in case the wife and I are doing separate errands and using both cars.
As for pluses and minuses on each car:
Prius - I think the Prius is a little more roomy. There is no battery hump in the back which makes for a more useful hatchback with folded down seats. The rear and front seat leg room seems better on the Prius. The voice recognition is better on the Prius than on the Leaf. You can just call out a destination with the address and city of your destination in one voice command on the Prius. I haven't found how to do that on the Leaf yet. At least not an address that is not in your address book. I still don't know how to speak an address that is not in the address book in voice command on the Leaf. I have had to pull over and stop to put in a new address. I may just not be doing something right, but that's a big negative for me on the Leaf in the navigation system. On the leaf you seem to have more menus to go through before getting getting to your goal. Even a phone call seems to take several commands before you get to make the call you want. There are two versions of the Prius Plug-in; the base; and the Advanced. The advanced version is about 7 or 8 thousand more than the base and you get drive assisted radar in cruise control and a bigger navigation screen with a few more options and also leather seats. Those bells and whistles are nice, but I don't think it's worth the extra 8 grand. On the Prius you can go anywhere as you can always fill with gasoline if needed. I get about 500 miles on a tank. You can fill a tank in a few minutes with the Prius whereas the Leaf could take you most the night depending on what kind of charger your connected to. The Prius is rated at 10-15 miles on a charge before it goes in the hybrid mode. That can vary significantly depending on terrain. If you are going down hill for quite some time, that mileage can be greatly expanded. I have driven well over 30 miles total coming down a 4000 ft mountain and using very little hybrid mode on mine for the entire 30 miles. The Prius takes about 3 hours to get from 0 to full battery charge on a 120 volt plug. 240 volt (level 2 charger) is about an hour.
Leaf - The Leaf is more expensive than the Prius Plug-in Base, but there are better state and Federal Incentives for the Leaf. The Prius is only eligible for 2500.00 Fed Tax Credit whereas the Leaf gets $7500.00 Fed Tax Credit. In California you get a 1500.00 rebate for the Prius and 2500.00 for the Leaf. I can't speak for your state if your not in California. The Leaf requires no engine maintenance. No Oil changes,, no spark plugs. You never use gasoline. There is no exhaust pipe so you can't even pull it into the garage and commit suicide with it while it's running in your garage. Both the Prius and the Leaf have XM radio, and I prefer the Leaf menus for the Radio. However, The Prius does have Pandora capability with it hooked through your cell phone service. The Prius also has Bing internet search engine available to find Points of Interest. The Leaf however has a search for charging stations which the Prius for some crazy reason left off. The Leaf has the Carwings App which allows you to control your car from your cellphone to turn on climate control and monitor charging status. The Prius only comes with an A/C on button on the key fob and you need to be a pretty close range to the car for it to work. The app for the Prius is called Entune. Entune has a few nice other nice things like weather, weather forecast, and even a Doppler weather radar image. But Entune does not give you the option of communicating with your car from great distances as Carwings does. Both have smart key entries which will spoil you if you hadn't had it before. With the Leaf you really need to think about investing in a Level 2 Charger. The level 1 charging is just really too slow and is not an efficient way of charging. I found a charge station for about 750.00 at Home Depot and had an electrician run the wiring from my electric panel which cost a few hundred more. I believe there is a fed tax credit of up to 30 percent of the cost of installing an EV charge station up to $1000.00. Many people spend around 2k to install a station, but it can be done for less. The Leaf takes about 20 hours to charge from 0 to full charge on a 120 volt charger. A Level 2 charge takes about 6 hours.
Some other thoughts: I don't care for how the "source" button on the steering wheel on the Leaf sticks out. It changes your radio station or audio source. If I'm driving with one hand for any reason and use one hand to turn the wheel, sometimes my palm will scrape against the source button which changes my radio station or audio source. That's happened a few times. Both the Prius and the Leaf have climate control buttons on the steering wheel. Volume controls for the stereo as well. I think the stereo sound is pretty much equal between the two. You might want to consider the climate of your home town. You get better mileage on your Leaf if you do not need to use climate control (turning off the A/C or Heat). On the Prius, it doesn't seem to affect the mileage quite as much. The Prius has heated front seats whereas the Leaf has heat buttons for front and back seats, as well as the steering wheel. Both the Prius and the Leaf are offering really good Lease deals at this time, just remember you are not eligible to claim the Fed Tax Credit if you lease. Nissan does give the tax credit back to the consumer in the form of a Rebate. I was able to get just under 10k in a rebate from Nissan on my lease. That makes up for it. Toyota has a different rebate offers depending on where you are located in the country. When I got mine in California the rebate was only 1000.00. I think it is now 1500.00. However I understand back east it is up to 4000.00.
On the Prius you won't be suffering from what they call "range anxiety", but you will still need to visit gas stations. However, On the Leaf you can proudly roll down your window and flip the bird to the gas stations as you drive by.
I hope this helps. Feel free to ask me any questions about the two.