Any of those years
except for a 2016. 2016 was a short model year and the first year of the refreshed styling. 2016s have had far more frequent issues. Overall the Volt is a very reliable vehicle, but the 2016 is the least reliable of those years.
Could you be specific as to the problems the '16 model Volt has that older models don't? I'm a used market guy that is always looking at the next upgraded model as a future used purchase. I had already decided to skip '16 but not because of any complaints I've heard.
My experience yesterday didn't make me feel any better about any issues I might encounter as a Volt or Bolt owner in the future...
I purchased my '14 Volt from a dealership 110 miles away. Yesterday I took it to that dealership for warranty maintenance service, after owning it for a couple of weeks shy of a year. It was time for the oil change even though I hadn't run the engine enough over the year to get below 44% of the oil life. I wasn't at all happy with the way the service dept rep tried to b.s. me as to the dangerously high voltage that lurks under the hood due to the crazy high voltage used in the battery...meaning only a 100% certified Volt mechanic can touch that car. I have little to no patience with service people who lie and scare customers. He was claiming those batteries are running over 20,000 volts! The charge station they advertise at that dealership is as a practical matter not accessible to the public. I was studying the Volt technology when he was still in middle school and retired from the IBEW after 30 years 10 years back. Before I became a wireman that worked everything from millivolts to lightning, I was a certified line mechanic at a dealership. Automotive tech has always interested me and I'm not the right guy to try and b.s. in that regard.
So... I got my scheduled warranty maintenance done and left after reaming the service managers butt for her service writer's ignorant arrogance and disrespectful attitude. On the way home I stopped at the Chevy dealer that is only 30 miles from my house. Since they advertise they have a charging station there, it occurred to me I could just have my services done there. Their charge station is also not accessible and they wasted no time telling me they wouldn't even change the oil on a Volt because they didn't have a 100% certified Volt mechanic. I don't see this as a positive sign for Volt owners. With the fact that GM is likely going to discontinue the Volt line in the not too distant future I see little incentive for dealers to spend money getting their mechanics Volt certified in the future. What you see now is what you will have in the future. Possibly much less, if the 1 mechanic they do have that is certified, gets pissed off and quits.
I also learned that there won't be a Bolt dealer within 300 miles of where I live.