I've had my Leaf for less than a month, so I'm certainly no expert, but my wife and I went through a very similar comparison when shopping for ours. We were mostly comparing 2013, 2014, and 2015 models, and they all had mileage ranging in the 20k's, 30k's, and 40k's. I think the highest one we looked at was 52k, and the lowest was 25k. 80k miles on a 2015 seems very high to me, at least compared to the options we had.
Most had 11 bars, one or two may have had 10 bars. That was the extent of my knowledge of the batteries, that plus reading about the 2012 and older models having problematic batteries. I wish I had known about Leaf Spy Pro during our shopping process, I would have used it extensively! But alas.
I think that seeing the different versions of the car and trim in person are important, but I'm not sure you really need to do extensive test driving...from the few I drove, they all felt exactly the same...driving a 2013 felt the same as driving a 2015. The differences are in the other features.
After researching and driving a few, we decided that we definitely needed to have:
Level 3 DC Quick Charge
Cloth seats (we don't like leather seats)
Things that were optional but nice to have:
A color we liked (blue, red, or dark grey....basically anything but silver)
The above checklist lead us to narrow down our choices to only consider the SV models, since we didn't want the leather seats in the SL models, and the S models lacked the other fancy feature we wanted. We were actually on our way to buy a 2013 SV with 42k miles from a 3rd party dealer, when my wife found an ad for a 2015 SV with 42k miles for about the same price, so we took a detour to a Nissan dealership to check it out. We test drove that one, decided it was a better deal, and found out that we would be getting a Certified Pre-Owned warranty from Nissan, which is definitely worth something (they told us no 3rd party dealers can offer that). So we started the process of buying that car....and after about 3 hours of paperwork and waiting we were told that the car had been sold by Nissan Fleet services to someone else! Needless to say we were pissed. So to make it up to us, the Nissan dealership offered us one of three other cars that had just come in, hadn't been cleaned or inspected yet. We chose a blue one, a 2015 SV with 25k miles. They matched the price of the other one we were going to buy, which is pretty nuts since this one had 20k fewer miles and 12 bars!
We then went through about another 3 hours of paperwork and waiting...the other stupid part of our story is that we had gone with the intention of buying cash, but Nissan has this program where it is actually $700 more expensive to buy in cash! So they convinced us to finance the car (we then paid it off in full, about 2 weeks later, incurring around $50 of interest).
So the final amount we ended up paying, including finance charges, DMV fees, etc., was: $11,562.32
We also got everything we wanted on the list above, no compromises! We just had to wait a few days for the car to be cleaned and inspected, then our dealer personally delivered the car to us (by hauling it on a trailer). We live about 2 hours from the dealership, so that was pretty nuts too!
The whole process was such a mess, I feel like this dealership's motto should be 'You'll go through an ordeal, but you'll get a good deal'.
We originally bought this car with the intention of replacing a 2001 Toyota Prius as our running errands vehicle. Now we enjoy it so much that we're planning long distance roadtrips in it!
So I guess my advice to you is this: if you are sure that this will just be commute vehicle and nothing else, then it isn't all that important which one you choose. As others have said, even a depleted battery will get you 20 miles without issue. However, if you think you may be swooned by the car into taking it on longer trips, then definitely pay a bit extra for a battery that is in better condition, and that has the features you want (especially QC, as roadtrips without QC aren't really feasible).
Also, I suggest buying from a Nissan dealership to get the CPO warranty...despite the awful experience we had, I think the warranty is worth it.
2015 Leaf SV, 25k miles, 12 bars