Tenergy 16 bay AA / AAA charger
This is the charger I use in my own lab. It's really pretty nice! It's not super fast, but it does a great job charging batteries. I think this one is at least three years old.
Now, I don't get a deal on these. I order hundreds of batteries, so I get a decent break on those. I couldn't buy enough of these to get any kind of break and I honestly don't want to deal with their storage. So I just order a couple to have around if a school needs one or two. Keeps it easy.