i recommend BF4 and BF1. BF4 is the most modern version of the classic battlefield style and there's still plenty of people who play.
BF1 is the only fully immersive WW 1 game that i know of, and they do an absolutely phenomenal job. old school tanks, planes, artillery cannons, boats and ships, weapons... conquest is a blast and there are still quite a few good servers (at least in the US) that are consistently packed with players
after CSGO, BF1 is probably the most-played game in my library