With the addition of the wrath classic token you now have the choice of two different versions of wow to make enough gold to play for free.
Discussion from Wowhead
The WOw head and woweconomy discussion focused mostly on very high end methods. Particularly for wrath with things like GDKPs and dungeon boosting. Both of which require you to be max level and have significant gear. This means the startup cost is very significant. Now on the other side for Retail the cost to get up to speed on professions is also extremely high, and time gated for profession knowledge.
Farming?
We’ll start by looking at farming to see how quickly you can earn a token just from farming. Max level farming in Dragonflight also suffers from Knowledge Point limitations, but there’s a ton of old zones you can go to.
Wrath classic
In Wrath Classic you can make between 600-800 gold per hour farming Mana Tombs on a reasonably geared level 80 character. A lot of the value will be from Auction House items, but you are mostly selling stuff with fairly high sale rates. This would put you at needing to farm for 10-13 hours to get an EU token.
Retail
In Dragonflight the consensus seems to be about 20 000 gold per hour, you can even get close to that with a raw gold farm doing the 2×4 in Forbidden Reach. With EU tokens on retail selling for about 400k you would need to farm for 20 hours to get a token on Retail.
Comparison
Obviously it’s a lot faster to farm on Wrath. The Wrath token is less useful, since it can only be used for game time, but if you just want to farm for a token, then spending an hour a day on wrath until you get a token is the way to go.
But what about optimal goldmaking?
GDKPs seem to be the fastest way to generate gold in any version of WoW currently. The numbers quoted in the woweconomy thread are through the roof. This does require a geared level 80 character though, so it’s not readily available.
Professions?
It’s very hard to directly compare professions, since you can have so many different approaches. Generally I think the Wrath AH is much easier to get gold out of with both professions and flipping, since it’s just your realm. You can also use stack sizing on top of that to enable methods like material flipping.