long time creeper, first time poster.
what will be the best bracket for play on SL ? i've been scouring the threads, seems like 10s, 19s, and 20s(vet?) i'd like to bring back my beefy boi (prot pally) and im curious as to which bracket will be best.
To expand on
@Chops response, here's a quick summary of what's been found so far for Shadowlands brackets.
F2Ps and vets will 90% likely cap at level 20, which opens up a tremendous amount of content and retains the fastest queues, by virtue of staying in battlegrounds and arenas with levelers. The power gap between F2P and vets should shrink to some degree. I imagine most twinkers will have at least one F2P or vet for casual play, just from the sheer population of the bracket.
19s may retain some interest when (if?) blizzard puts a level requirement on epic mount speed. Three brackets with long traditions (old 19s, 29s, and 39s) get squished into this bracket, and even with the lure of SL 20s, SL 19s will always have the allure of being the lowest twink bracket.
29s have a good number of soon-to-be grandfathered characters from the 70-79 bracket that could provide a solid foundation for that bracket. From a stats perspective, the grandfathering of those characters provides only a very slight advantage in stats i.e. one consumable's worth, so new SL 29s won't feel dissuaded from trying the bracket where most classes really start to come into their own. If Blizzard fixes TBC raids and heroic dungeons to require SL 27 instead of SL 30 to enter, it's entirely possible that newcomers to the bracket may choose to go level 27 for outside-of-instanced-PvP scaling, and for tradition. While less populated, a few old 59s, 60s and 69s may join this bracket as well.
39s (old 90s, 91s, and 99s) are already organizing, gearing, and preparing for shadowlands. Much of their best gear comes from the Siege of Orgrimmar and Throne of Tides raids, which many of them have. If you're looking for more of the old-school camaraderie where people collaborate on both factions to surmount the more difficult gear requirements, SL 39s may be for you. The higher gear level also reduces the impact of unscaled gems, but with so many other variables in play in Shadowlands, who knows what that means.
I haven't heard anything going on with SL 49s yet.