As I expected, more than a few jabs at the newer setting, Age of Sigmar, from some old-school players. I think it's important to note that Age of Sigmar exists for a reason, and has more than just a few fans. Even a few fans who've been around for a while!
Old-School Warhammer Fantasy, both the miniatures game and the RPG, are very grimdark . . . pretty sure Warhammer is where the term "grimdark" comes from. It's very
heavy metal, but with an gritty, grungy, 80s, British aesthetic . . . not surprising since it was first published in the 80s, in England! The old-school RPG has a pretty hardcore, enthusiastic fanbase, and for good reason. Old-school Warhammer is the setting for the Total War and Vermintide video games, among others.
New-school Warhammer, Age of Sigmar, has a lot in common with it's predecessor, but has a very different tone and feel. It doesn't totally leave grimdark behind, but is much more high fantasy. It's REALLY high fantasy, the "highest" I've come across. It's also pretty
heavy metal, but more high-brow, almost surrealistic, maybe more
prog-rock than heavy metal . . .
As mentioned above, Age of Sigmar isn't a typical fantasy setting like the old-school Empire, where you have adventures on the mortal plane. Rather, it's more of a planar campaign where you adventure across multiple, fantastic planes of existence. Each plane has a theme like fire, life, death, beasts. light, metal, and shadow. But unlike D&D's planes, each is a "mortal realm" where the humans, elves, and dwarves live. The planes are connected by gates, and the major conflict is between the forces of law and the forces of chaos.
Which is better? Both! Neither! Whichever one seems the most interesting to you! Like any fandom, there's a lot of old-school crankiness aimed at the newer setting, but ignore all that. Both settings are pretty awesome places to adventure within an RPG, or a mass-battle miniatures game!
Personally, I was in middle school when Warhammer first became a thing . . . and the grungy grimdark setting turned me off and I never had any desire to try out the miniatures game, or later the RPG. I still don't really care for the style and tone of old-school Warhammer (
strangely, however, I do enjoy Warhammer 40K, the space fantasy version of the game). I dig the Age of Sigmar setting a lot and play the miniatures game. I haven't picked up the new RPG yet, as I'm not usually into fantasy games that are close to D&D, but aren't D&D . . . I would love to check out a fan-design of AoS ported to D&D 5E!