If it’s World farming you’re after …
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Make a Havoc Demon Hunter.
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Level it to 111, and the minute you hit 111, lock your XP. This is because the perceived level of mobs depends on you being below halfway to 112. If you lock your XP at the start of 111, everything will appear 110 to you, and that makes things easier.
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Buy crafted 225s (cheaper) or 233s. In truth, either will do. Pick up your Heart and your 3 280 Azerite pieces.
You now have the best farmer you can get for your faction’s Island in BfA. The downside is that the mobs on the other faction’s side appear 120 to you, so that’s a no-go.
- When you build up a bit of cash, buy The Sentinel’s Eternal Refuge crafted Legion legendary. It gives you insane mobility. Wisp form FTW!
I have done this on both factions, just because I was curious, and then because it’s about the only fun I could find in BfA. It surprised me that it is fun. The Sentinel’s Eternal Refuge is endless fun - I’m so sorry I never bought any of the crafted Leggos in Legion now.
Your DH can now simply delete EVERYTHING, in any quantity you can pull, on your faction’s island, with two exceptions:
- Any mob that appears to you as 120, but there are not many of those - World Boss, opposing faction’s PvP camp guards, an occasional WQ boss that should be 110 to you but seems bugged (most do appear 110).
- The marching Blood Troll Warriors that keep crossing that path in Nazmir in large numbers. On my Horde 111 DH, I can chain pull packs of 6 out of the parade all day without losing health, but I can’t just stand there and destroy everything that passes.
You can also destroy old raids up to and including Warlords. (P.S. You can farm Pandaria twice each week: once entering normally, and once through the Raid Finder Storyteller. Each farm nets you over 5K raw gold, so 10K++/week from that alone.) Also Islands - everything just melts before you.
Another great advantage is that it’s quick to level a DH to 111.
If you really want to supercharge your farmer, you can get a boost through Antorus Mythic to pick up gear from there, and if you aspire to selling Freehold boosts, you will want to do that. My twinks can solo Freehold and Atal’dazar respectively, but not fast enough to make it a commercial proposition. If you really want to get into it, there is an excellent guide on xpoff.com , but I haven’t bothered, at least not yet. You don’t need an all-out twink for world farming.
I have settled on Herb and Skinning as farming profs. Yes, one might usually say Herb/Mining, but the DH can pull and delete packs of 10-20 so fast that you can get skins at a crazy rate when you have the BfA Skinning enchants on your hands.
If you want a demo, I could meet you on my Alliance. He’s my 110, and not as powerful as the 111[*], but I could show you a taste. 
P.S. For pure volume mob grinding, I do not recommend a Hunter - at least either ranged spec; I’ve never even looked at the new melee spec. Hunters are great at soloing hard targets, but when it comes to mowing down masses of lesser enemies continuously, they hiccup Focus, which slows you down.
[*] The theorycrafting for 110/111 DH is sketchy. My belief after reading and watching around is that IF you go all out, and get optmised Antorus M gear, 110 is better, but if you’re not that energetic, the crafted BfA greens and blues give the 111 a noticeable edge. Either way, you want the best Azerite traits. Also, your stat prios will not be as for 120s; it is possible that the Legion Leggo Head + a Mastery build focusing on EyeBeam, Shards and Leech is optimal - but really, unless you’re setting up a boosting business, it isn’t going to matter much; the DH is just SO powerful and SO fast in the world that you will barely notice.