My opinion
Golden Era/Hulkamania: 1984-King of the Ring 1993 (Hogan's last match in the WWE until 2002)
New Generation: 1993-Wrestlemania 14.
The rise of the Hart brothers, HBK, Undertaker, Diesel, Razor Ramon. Athleticism and workrate is emphasized more than big muscles. Also a low point in the WWE with Raw's taking place in high school gyms and small ass arenas in small markets, ridiculous gimmicks. A lot of money being lost.
Attitude Era: Wrestlemania 14-Wrestlemania 17. Shawn Michael's last match until 2002. The Undertaker is the last big New Generation era guy left. Austin and The Rock become megastars. Adult oriented content is emphasized at the expense of workrate until Russo leaves. I believe the WWE actually acknowledges the attitude era ending at WrestleMania 17.
Ruthless Aggression era: 2002-2007. This is kind of tricky because after Wrestlemania 17 the company was still doing attitude era stuff but it really wasn't the attitude era. There was no competition in the beginning and they had one of largest rosters in company history. This is around the time I stop watching on a regular basis. Probably watched Raw and Smackdown a total of ten times during that period but kind of kept up with was happening by reading on wikipedia Wrestlemania, Summerslam, and Rumble results. IMO this era ended when Benoit murdered his wife and kid.
Unknown era/somewhat safe era/PG era: 2007-2011. I don't know what to call it tbh. Wrestling was in the limelight for the wrong reasons (Benoit), Linda running for office. The WWE really becomes corporate at this point even though they had gone public in 1998. Wellness program is implemented. Also started seeing a influx of Hollywood writers. I really can't say much because I really wasn't watching at this point.
Reality Era: 2011-2014. Basically started with Punk's pipe bomb. Saw The Rock and Brock Lesnar return, Daniel Bryan's rise, Triple H taking a step back from the spotlight, social media being incorporated into the product, etc.
Network Era: 2014-Present. The launch of the WWE Network.