After playing both Doom 2016 and Doom Eternal, I find 2016 to be far better made. I like that Doom Eternal added in some cool features like fighting on Earth, Battlemode, new gadgets, destructible monster weapons, and brought back Doom 2's mounters. But Doom 2016 had training mode bots you could spar with if you aren't up to fighting humans, SnapMap, and took less space on my HD.
Flame Belch is cool and all, except you need to use it. A lot. It doesn't seem to do damage; just makes it so damage done to the enemy set on fire drops armor like monsters from the Quake 3 Arena mod known as the "Hunt Mod" (that mod is a lot of fun IMO). The parkour is not necessarily a bad thing to have in the game, but Eternal fucked up by shoehorning these mechanics in to the point where they were less novel and cool, but a pain in the ass that made me switch to 2016 just so I wouldn't have to do it anymore. Eternal seems to be for the "hardcore gamers", but 2016 was the one I find more fun. And after 2016 had bot support I got Eternal hoping Battlemode at least had bot support. As far as I could tell, it doesn't even have that. How could someone call Doom Eternal an improvement when the utterly gutted the multiplayer/skirmish when that is like half the game itself?
In the Doom community, that's apparently an unpopular opinion because most of these new Doom players don't want to use SnapMap or other map editors to make fun custom user content, but play a game of "do the choreographed dance to not die". I'm not having a good time, what's the point of playing?