Ohhh...let's see:
2012: Last year before the 2013 mid-model refresh. So there's actually a lot of differences. Depends what those matter to you: Last yr for Hydraulic steering (No 2,500 dollar surprise!!!), Older front grill trapezoidal styling, More basic wiring (less crap to fail!), RFE 6-spd tranny with a REAL dipstick!!! and easy to service. Some have a REAL cable-run column gear selector. Not as many or good or current tech options ...if that matters to you. Trailer brake may or may not be integrated as well...depending on pkg. Seats wear out on bottoms. Easy to plug in your scanner and do things via OBD.
2018: Updated electric steering (so it's been reported), vs pre 2018 Rams (so it *should* be more reliable???), Cams/lifters are 'said' to be improved in 2018, 8-spd tranny, better and more current infotainment features. That could be good/bad...as LCD's and crap aren't forever, and at some point they'll stop updating those things. Most of the wiring bugs worked out vs 2013-2017 trucks. Need to use a secure gateway to access the OBD stuff. It's a hassle, not a deal-breaker.
Overall, b/c you live in CT, I would be more concerned about rust. Older Rams can rust like the dickens. Unless the 2012 has been heavily undercoated...which I doubt, or is from down S. I would expect it to start rusting like crazy soon.
More than likely the 2012 will need things like shocks/brakes, unless recently replaced ...and are the rear axle arm bushings still good?
Overall, I would lean towards the 2018 all else being equal...which in the real world things never are, lol
. A 2018 is better than a 2014. But if the 2012 is real clean, and the above items fit into your wheelhouse, certainly nothing wrong with a 2012, esp if you do more of your own work and the tk is cheap enough. If you're a guy who just wants to drive and not do any work, expects the tk to look great for yrs to come, it's a no-brainer ...get the 2018 and get it undercoated...and if you can, maybe get a simple powertrain warranty to protect you from any cam/lifter surprises.
Best Regards