Besides the excellent point from OK4450, I think the transmission could be a pivotal factor. That’s because transmission rebuilds are quite expensive.
The most knowledgable contributors on this forum frequently stress the importance of regular fluid changes (with new filter generally) for auto transmissions every 30,000 miles, which translates into much longer life for an auto trans. You mentioned the lack of service records on the Nissan, unfortunately. At least see if you can find out the history on transmission service for the Camry. If the transmission service for both cars had been about the same (and are there records of that), then you can take that out of your calculations. However, if the Camry has been meticulously maintained with regular trans fluid change, and the Nissan has never had a transmission service, then you might lean toward the Camry. You could also drop in at a transmission repair shop, preferably a locally owned independent one, and see if they have any thoughts about the durability of the transmissions in these two cars.
But it sounds like you can’t get any info on the Nissan for the first 12 years, so look at it this way. If you assume that you’ll put nearly 40,000 miles on the car, you might never encounter a problem with the Nissan since that would get you to around 165k. But add the same 40k to the Camry, and you are starting to verge into the time when a transmission may have problems.
I am inclined to think that the Camry is being priced higher just because it’s a Toyota, and to some extent because of the bells and whistles which you say don’t matter to you.
You seem more focused on reliability and value, and for that reason, the Sentra sounds like a better value for your criteria.
It all comes down to the condition of the car. Forget the nameplate and go with what the mechanic says when he checks the cars.
Art1966 adds another key point. Good luck!