You can’t go wrong with a mage. In fact, Mage was the most popular class in World of Warcraft: Classic due to their ability to farm with ease. Back in the day, the player majority even leveled mages as alts in order to gather gold quickly. In addition to their monstrous ranged DPS, mages also have tons of useful utility. As a mage, you’ll be able to conjure food and water, place portals to the major cities, and even earn gold from doing so.
Some even more advanced gold makers might also attempt to monopolize the market. It’s fairly easy if you have quite a bit of gold – just buy out every single item on which you want to have a monopoly on and then reintroduce it to the auction house with your new (and higher) price. However, it’s worth mentioning that monopolization tactic is risky business practice. But where’s high risk – there’s high profit.
Making "new" guides seems kinda out of place. Not only is there still alot of information from back then available, there came alot of information up for minmaxing available for both leveling and raiding, ontop of various bis gear lists that cover patch progression aswell if necessary. Wether people like or dislike pservers does not make the various information found on their forums less valuable.
And for talent builds. I prefer to make my own talent builds. But I've been playing RPGs since the 8bit days so half the fun is building my own characters up. I already made and bookmarked 1 deep fire mage build, 2 elemental mage builds, and 2 deep frost mage builds. And I might remake them tomorrow if I read up on any good talent choices I left out my 1st 5 times lol. And I have multiple builds for the other classes I play too.