I have been playing WoW since launch, never a super [H]ardcore player, but I would say more than casual. I am a serious casual player, if there is such a thing. I play 6 nights week, after the kiddies go to bed, I play for 90 min or so, and then longer on a weekend night or two.
In Legion I ran current Normal raids, and partial heroic raids, when they were fresh and new. And I always ran M+, typically in the M+10 to +13 range.
I had 4 level 110 mains I played almost equally, in Legion, they were ok geared, like i955 - i960 or so towards the end.
Fast forward to BfA, I roll a fresh boosted level 110 Blood Elf Rogue, and I rush through to get to 120. Start doing end game, and gearing up in dungeon runs, etc...I get to i340 or so pretty quickly after launch, and start feeling sort of burned out, and frustrated with BfA, and then I start nitpicking the expansion and getting upset with it. After week 2, I was mad about BfA, and not a happy camper.
That has all changed now...
I said WTF, let's take a different approach here. I put the brakes on, and SLOWED down. I faction changed two of my mains from Horde to Alliance, to get a different perspective ( I have been with Horde since BC, haven't played an Alliance character since vanilla ) and I LOVE the change of scenery and different take on the Alliance side, and I really really like the Alliance zones in BfA for leveling, much more so than the Horde zones.
Right now my Night Elf Unholy DK is 118, and my Night Elf Fury Warrior is 111, and I am taking it slow, and enjoying each zone, and in no hurry to get to 120. And I also really really want a Void Elf bad, so I dusted off my Paladin, that was 10k / 21k revered with Arguss Reach in Legion, so I am playing my Paladin in Argus zones again each night, getting the rep up, to be able to unlock the Void Elf's. Right now I am 14k / 21k revered after 3 nights.
And this laid back relaxed play, and switch to Alliance has been a pleasant experience. I look at it this way, BfA is brand new, there's no rush to end game and to be i370 geared immediately, because why ? There will be a new patch with a new Raid and catch up gear, etc...happens each expansion, Blizzard makes catching up pretty easy and quick.