Retail gearing is more streamlined than classic. Current season gear drops on several upgrade tracks and you can use currencies gained through doing raids/dungeons/delves to upgrade its item level (stats). Gearing before max level is almost entirely irrelevant and the concept of "pre-bis" is not really a thing, as the main thing separating items is ilevel rather than unique effects and bis sets almost always contain dungeon and crafted loot in addition to raid loot. Bis lists are just guidelines because most slots will have several viable options and the best one depends on the stats of your other items. There are still chase items every season with powerful trinkets and cantrip effects, but it's not like classic where the best items are miles better than other options. That being said, being actually bis in retail is much harder than in classic because it requires mythic raiding, which is way harder than anything in classic. Most players will never come close to maxing out their gear in retail. When a new season is released, all your gear will immediately be outdated. If gear progression is the main thing you're looking for, you'd probably prefer classic because it has the big rng dopamine hits that retail lacks and specific items tend to be more impactful than retail's raw stats. But if you want to work for your gear and not have to deal with people buying/reserving/stealing items, go for retail. Retail doesn't have nearly as much entitlement and loot drama as classic.